15.3

Milestones in Gender Development Developmental psychologists have identified general patterns occurring over the course of most children’s gender development. As reviewed in this section, gender-related changes are evident in children’s physical, cognitive, and social development. Prenatal Development Sexual reproductive organs are formed during prenatal development (see Blakemore et al., 2009). A typical biological female infant’s internal reproductive organs include ovaries, fallopian tubes, and a uterus; and her external genitalia includes a clitoris and labia. A typical biological male infant’s internal sexual organs include testes and ejaculatory ducts (vas deferens); and his external genitalia includes a penis and a scrotum. Typical Prenatal Sexual Differentiation Around 6 weeks after conception, the gonads (either ovaries in females or testes in males) are formed. If the embryo is a genetic male (XY), the SRY gene (sex-determining region of the Y chromosome) will trigger the differentiation of the gonads into testes. Otherwise, in the absence of the SRY gene (as with a genetic female), the ovotestis will differentiate into ovaries. Next, around 7 to 10 weeks after conception, the embryo forms two sets of ducts or tubes in both genetic females and males: the Müllerian ducts (that can differentiate into fallopian tubes and a uterus) and the Wolffian ducts (that can differentiate into the ejaculatory duct). Typical male embryos will begin to produce two hormones in their testes: testosterone and Müllerian inhibiting substance (MIS). Testosterone triggers the development of the Wolffian duct into the ejaculatory duct. MIS stops the development of the Müllerian duct and therefore fallopian tubes and a uterus are not formed. In the female embryo, the ovaries do not produce MIS or testosterone; therefore, the Müllerian ducts develop into fallopian tubes and a uterus while the Wolffian ducts atrophy. The final major step in prenatal sexual differentiation happens between 8 and 12 weeks after conception when the external genitalia are formed. Genetic males begin to produce dihydrotestosterone (DHT), which triggers the development of the external genitalia into a penis and scrotum. In the absence of DHT, female external genitalia develop into a clitoris and labia. (The scrotum is essentially the fusing of the two sides of the labia.) As this process illustrates, prenatal sexual differentiation is characterized by bipotentiality. To some extent, the embryo has the potential to form female or male sexual organs depending on the presence or absence of particular hormones. Variations in Prenatal Sexual Differentiation The presence or absence of particular hormones, such as testosterone, MIS, and DHT, typically determine whether the embryo forms male or female internal reproductive structures and external genitalia. In the absence of these hormones, the default is towards female organs and genitalia. However, this typical pattern of development sometimes does not occur. In rare instances, a person of one genetic sex may either develop the sexual structures associated with the other genetic sex or undergo only partial development of sexual structures associated with their genetic sex. These are known as intersex conditions (Preves, 2003) or differences in sex development (Sandberg & Gardner, 2022). There are multiple intersex conditions. Two of them, congenital adrenal hyperplasia and androgen insensitivity syndrome, have been of particular interest to gender development researchers. Congenital adrenal hyperplasia (CAH) is associated with a recessive gene that leads to the production of high levels of androgen hormones during prenatal development. These high levels of androgens can lead to the formation of partly or fully masculinized external genitalia in genetic females, such as a clitoris that is enlarged and may resemble a penis. In contrast, because there is no production of MIS, the internal reproductive structures are usually unaffected. Researchers have found that genetic females with CAH were more likely than those without CAH to choose physically active forms of play (e.g., rough-and-tumble play) and to avoid sedentary forms of play (e.g., doll play; Berenbaum, 2018; Hines, 2013). Most genetic females with CAH self-identify as girls (Hines, 2013). These behavioural tendencies do not appear to be caused by parents’ treating them differently because of their masculinized genitalia (Hines, 2013). In cases of androgen insensitivity syndrome (AIS), a recessive gene leads the androgen receptor cells to malfunction in genetic males. Although increased production of testosterone (a type of androgen) may occur during prenatal development, the hormones do not trigger the typical physical changes in sexual differentiation. In these cases, genetic males with complete AIS develop neither male internal reproductive structures (because testosterone does not trigger development of Wolffian ducts) nor female internal reproductive structures (because MIS arrests development of Müllerian ducts); hence, they will be infertile. In addition, they are born with female external genitalia (because testosterone does not trigger development of male external genitalia). Boys with AIS typically show preferences for stereotypically feminine interests, and they commonly self-identify as girls and later as women (Hines, 2013). Cases of children with CAH and AIS offer evidence to support the premise that prenatal androgens may partly contribute to boys’ and girls’ brain organization and their later gender identities and gender-typed play preferences (Berenbaum, 2018; Hines, 2013). However, it is important to reiterate that there are normal variations within each genetic sex in their exposure to prenatal androgens as well as in their later preferences for different kinds of activities and interests. Furthermore, there are multiple influences on children’s gender development. Thus, a person’s biological sex does not always fit binary categories of female or male. First, as noted earlier in the chapter, there are persons with a chromosomal sex that is neither 46 XY or 46 XX—such as those who are 45 XO, 47 XXY, 47 XYY, amongst others. Second, there are persons whose external genitalia may differ than what is typically associated with 46 XY or 46 XX chromosomal sexes. Examples include genetic males (i.e., XY) with AIS who have female external genitalia as well as some genetic females (i.e., XX) with CAH who may have male external genitalia. Video: Understanding Intersex One of the controversies regarding children with intersex conditions is whether surgical interventions should be taken after birth (Roen, 2019). For example, in the case of genetic females (i.e., XX) with CAH with an enlarged clitoris resembling a penis, surgeries were commonly performed to make the genitalia appear more similar to a typical clitoris. Over the years, an increasing number of adults with intersex conditions and their advocates have challenged the premise that their anatomy needs to be “corrected” to conform to binary notions of sexual anatomy. They also argue that decisions about surgery should be made later by the individual who is affected (see InterACT, n.d.). Infancy and ToddlerhoodThe first two years after birth are a period of remarkable growth and change in the child’s physical and cognitive development. At birth, on average, male newborns weigh about half a pound more than female newborns do. During infancy and into childhood, females and males grow at approximately the same rate and are generally equal in height and weight (see Chapter 3). By the end of the first year, babies are capable of perceiving the physical features that typically differentiate adult women and men. And by their 2nd birthday, they are beginning to establish a verbal concept of gender that will quickly organize how they view the world and themselves. As we saw in Chapter 5, research indicates that infants can detect complex regularities in perceptual information (e.g., detecting differences amongst different geometric shapes) through a process known as perceptual categorization. Clothing, hairstyle, height, head and body shape, motion patterns, vocal pitch, and activities all tend to vary with traditional gender expressions amongst women and men; these differences provide infants with gender cues that become the bases for the perceptual categorization of people’s gender (for a review, see Rennels & Kayl, 2017). To test these perceptual abilities, scientists commonly use visual preference or habituation–dishabituation methods (see Chapter 2) to infer whether infants detect differences between prototypical female and male models. These studies reveal some remarkable patterns. By 4 months of age, infants are capable of recognizing differences between the faces of prototypical adult women and men. Around 6 months, infants can associate faces and body types for prototypical women and men. Within a few months later, infants also connect the faces and voices of prototypical women and men. Although infants do not yet understand anything about what it means to be a woman or a man, they increasingly recognize the physical differences between prototypical women and men by using multiple perceptual cues (Rennels & Kayl, 2017). As they get past their 1st birthday, toddlers begin to show evidence that they have formed conditioned associations about some objects and activities that are repeatedly linked with prototypical boys and girls in their experience. For example, research by Diane Poulin-Dubois, Lisa Serbin, and their colleagues at Concordia University in Montréal showed that 18-month-olds looked longer at a doll than at a toy car after viewing a series of typical girls’ faces, and they looked longer at a toy car than at a doll after viewing typical boys’ faces (Serbin et al., 2001). The researchers inferred these young children expected the doll and the toy car to be linked with girls’ and boys’ faces, respectively. In another study with Canadian 24-month-olds, counter-stereotypical matches of adults’ gender and action (e.g., a man putting on lipstick) led to longer looking times; it appeared that the children were surprised by the action’s gender inconsistency (Poulin-Dubois et al., 2002). These studies suggest that at young ages children are learning to form gender-stereotypical conditioned associations—presumably based on their prior experiences of observing these patterns in their environments. Early Childhood During their second year, children increasingly use language to form concepts, or mental categories, to label and understand their worlds (see Chapter 7). Concepts are defined by particular attributes. The clearest evidence that children have acquired a concept of gender—that is, a conceptual categorization of gender—occurs when they verbally label people’s gender. By age to 3 years, most children use gender terms such as boy and girl in their speech to refer to themselves and other children (Fenson et al., 1994; for a review, see also Martin et al., 2002). At first, these concepts are based largely on perceived physical attributes and then extend to activities and other qualities. Once they self-label their own gender, children have begun to establish a gender identity. As we will review in the last section, Patterns of Gender Development, there are multiple facets to a person’s gender identity. Developmental psychologist Kristina Olson and her colleagues have conducted research on gender identity development in young transgender children (for reviews, see deMayo, Jordan, & Olson, 2023; Olson & Gülgöz, 2018). In one study with 5-year-olds, the gender identities (i.e., self-labelling) of transgender girls and boys, respectively, were equally as strong as those of cisgender girls and boys (see Olson & Gülgöz, 2018). Therefore, the research indicated that transgender children were not confused in their gender identity. Once children form mental concepts of gender, they seek to understand their gender identity—and what makes their gender ingroup distinct. This process includes learning what is typical for girls and boys in appearance, interests, and social norms. According to gender schema theory, children use their ingroup/outgroup schema to discern what is “for me” or “not for me” based on their self-identified gender. In turn, knowledge about their own gender informs their own developing gender identity (Martin et al., 2002). From 2 to 6 years of age, children are rapidly learning gender stereotypes (which are incorporated in their gender schemas). These stereotypes occur in multiple content domains (Ruble et al., 2006). Children’s earliest gender stereotypes are based on appearances (e.g., hair styles, clothing) and activities (e.g., toys)—which are easily observable characteristics. By about 3 years of age, most children begin to associate certain toys and play activities with either girls or boys. By about 5 years of age, they additionally may form gender stereotypes about personal-social attributes. These include associating affiliative traits (e.g., nurturance and warmth) with girls/women and associating assertive traits (e.g., aggression and directness) with boys/men (Biernat, 1991; Liben & Bigler, 2002; Serbin, Powlishta, & Gulko, 1993). Similar patterns have been observed across diverse cultures (Best & Thomas, 2004). Finally, as they get older, children begin to form gender stereotypes about roles and occupations (e.g., homemakers, firefighters). In the United States and Canada, children’s play becomes differentiated by gender during the preschool period; most girls prefer to play with soft toys and to spend time in the “housekeeping” area, and most boys prefer to play with blocks and transportation toys. Gender Attitudes and Behaviours Once children form stereotyped beliefs about gender, they commonly form evaluative judgements—or gender attitudes—about individuals who either meet or violate their stereotypical expectations. Gender attitudes underlie people’s behaviour when they praise others for enacting gender-typed behaviour (e.g., complimenting a girl on her feminine appearance) or they criticize others for enacting cross-gender-typed behaviour (e.g., teasing a boy who plays with dolls). Due to limitations in their cognitive flexibility, preschool-age children can be highly rigid in their gender stereotypes and attitudes (Halim et al., 2014). During this period, children usually do not understand that gender remains stable across time and consistent across situations (known as gender constancy and more fully described in the later section on middle childhood). For example, a preschooler might think that a girl becomes a boy if she cuts her hair, or that a boy becomes a girl if he wears a dress. Young children are also prone to essentialist thinking in believing that observable physical and behavioural attributes are inherent and essential to being categorized as girls or boys (as explained in the discussion of DIT). Although essentialist thinking is seen at all ages, it is especially strong during early childhood due to developmental limitations in children’s cognitive flexibility. Researchers found essentialist thinking about gender was also common amongst transgender children (for reviews, see deMayo et al., 2023; Olson & Gülgöz, 2018). Although these studies did not focus on nonbinary youth, research with adults indicated gender essentialist thinking was less likely amongst nonbinary persons than either cisgender or transgender persons (see Schudson & Morgenroth, 2022). Gender-typed play and interests Many children begin to demonstrate preferences for some gender-typed toys by about 2 years of age. These preferences become stronger for most children during the preschool years (Weisgram & Dinella, 2018). Indeed, during childhood, some of the largest average gender differences are seen in toy and play preferences (see Table 15.1). Cisgender boys are more likely than girls to favour construction toys, balls and physical activity, toy cars and vehicles, and action-adventure play. Conversely, cisgender girls are more likely than boys to prefer dolls, dress-up, and playing house. Although studies find large average gender differences in play preferences, there is still some variability amongst children. First, variation exists within each gender group in how strongly particular children favour gender-typed over cross-gender-typed play. That is, many cisgender children are very rigid in their preferences for gender-typed toys and play activities, whereas others are more flexible (Blakemore et al., 2009; DeLoache et al., 2007). Second, some children strongly prefer cross-gender-typed play and dislike gender-typed play. As previously described, this latter group includes genetic females with CAH and genetic males with AIS. In addition, transgender children usually prefer the play activities typically associated with their self-identified gender (deMayo et al., 2023; Olson & Gülgöz, 2018). Gender-segregated peer affiliations The preschool period is when gender segregation emerges. This occurs when most children begin to affiliate primarily with same-gender peers and to avoid other-gender peers (Leaper, 1994, 2022; Maccoby, 1998). Gender segregation usually begins around 3 years of age and increases steadily until about 6 years of age; and it then remains stable throughout childhood (Figure 15.4). Same-gender peer preference has one of the largest effect sizes in behaviour seen in childhood (see Table 15.1). Preference for same-gender peers is commonly seen across different cultures (e.g., Munroe & Romney, 2006; Whiting & Edwards, 1988; for a review, see also Leaper, 2022). Also, transgender children prefer affiliating with peers who are the same as their self-identified gender (see deMayo et al., 2023). FIGURE 15.4 Gender segregation in play This graph reflects the increase in social playtime between preschool and grade 1 that children spent with playmates of their own gender and the decrease in playtime with playmates of the other gender. (Data from Maccoby, 1998) Gender-segregated peer groups are a laboratory for cisgender children to learn what it means to be a girl or a boy. Peers are both role models and enforcers of gender-typed behaviour. Documenting these effects, Martin and Fabes (2001) identified what they termed a “social dosage effect” of belonging to same-gender peer groups during early childhood. The amount of time that preschool or kindergarten children spent with same-gender peers predicted subsequent changes in gender-typed behaviour over 6 months. For example, boys who spent more time playing with same-gender peers showed increases over time in aggression, rough-and-tumble play, activity level, and gender-typed play. Girls who spent more time playing with same-gender peers later showed increases in gender-typed play and decreases in aggression and activity level. Over the course of early childhood, peer pressures may further motivate children to favour same-gender peers (Miller et al., 2013). Behavioural compatibility may become less critical with age as a motivation for gender segregation. For instance, researchers observed physically active girls frequently played with active boys during early childhood; however, as these girls became older, they tended to affiliate more with girls—even though their activity preferences were more compatible with the boys (Pellegrini et al., 2007). Therefore, as children get older, ingroup belonging and conformity pressures may become stronger incentives than behavioural compatibility for affiliating in same-gender peer groups. As they assimilate into same-gender peer groups, children increasingly adopt similar interests and behavioural styles as their same-gender peers (e.g., Martin & Fabes, 2001). For example, girls who were once highly active may become less active if that is the norm amongst their same-gender peers. During preschool, children begin to avoid peers who violate gender-role norms, and by age 5 to 7 years, they will actively tease peers who cross gender-role boundaries. This is especially true for boys who are likely to experience peer rejection if other children observe them playing with dolls and other toys strongly stereotyped as appropriate for girls. For some children, assimilating into same-gender peer groups may be a challenge. As explained earlier, some children demonstrate intense cross-gender-typed interests. For example, some girls may strongly prefer physical activities and rough play while some boys may strongly prefer dress-up and doll play. These cross-gender preferences can create dilemmas. Many cisgender children reject peers who do not adhere to social norms in their peer group. Similarly, many parents and other adults disapprove of gender nonconforming behaviours in children (Leaper, 2015a). As a consequence, children with strong gender nonconforming interests may face a conflict between social pressures and their interests. This conflict puts them at risk for depression, anxiety, and other adjustment difficulties (Connolly et al., 2016; Olson et al., 2016). Also, gender nonconforming children may not feel like they belong with their gender ingroup, and perhaps this contributes to some of them adopting a different gender identity (see Leaper, 2018, 2022). Middle Childhood During middle childhood (approximately ages 6 to 11 years), cisgender children generally remain highly gender-typed in their attitudes and behaviours. However, age-related increases in cognitive flexibility provide them with the capacity to recognize variability in how gender is expressed. Based on a meta-analysis of several studies, gender stereotyping was generally more common amongst boys than girls during middle childhood, although the effect size was small (Signorella, Bigler, & Liben, 1997). Gender Constancy Around 6 years of age, children have developed what the developmental psychologist Lawrence Kohlberg called gender constancy (Kohlberg, 1966; for a review, see also Blakemore et al., 2009). Prior to attaining gender constancy, younger children may view a person’s gender identity as changing depending on how they dress and act on a given occasion (e.g., a child wears overalls and plays with a ball one day and then wears a dress and plays with a doll on another day). Gender constancy is indicated when children understand that a person’s gender identity does not typically change over time (gender stability) or across different situations (gender consistency). Gender constancy emerges at the same age when children begin to understand Piagetian conservation problems (see Chapter 4). Because children now appreciate that gender is not necessarily tied to a person’s physical appearance or actions, middle childhood is a period when they often show a bit more flexibility in their gender stereotypes and attitudes than in early childhood (Katz & Ksansnak, 1994; Liben & Bigler, 2002; Serbin et al., 1993). Although Kohlberg did not consider the possibility of children with transgender or nonbinary gender identities, Olson and her colleagues have observed that gender constancy emerges in transgender children. However, these children were more likely than cisgender children to express the view that a person’s gender could sometimes change (for reviews, see deMayo et al., 2023; Olson & Gülgöz, 2018). This difference is not surprising given transgender children’s own experience involved changing their birth-assigned gender identity. Also, many of the cisgender siblings of the transgender children believed a person’s gender could sometimes change—perhaps due to their own experience observing their transgender sibling. Video: Is Gender Identity Biologically Hard-Wired? Due to gains in cognitive flexibility, gender stereotyping is usually less rigid during middle childhood than early childhood. Nonetheless, it is still very common for cisgender school-age children to endorse gender-stereotyped beliefs and to enforce gender conformity (see Halim & Ruble, 2010). In contrast, research indicates that transgender children may be less likely to endorse gender stereotypes than their cisgender peers (see Olson & Gülgöz, 2018). Societal Understanding of Gender During middle childhood, children start to show a clearer understanding that gender roles are social conventions as opposed to being fixed to the person’s gender (Carter & Patterson, 1982; Rogers, 2020; Stoddart & Turiel, 1985; see also Chapter 14). As children appreciate the societal basis of gender roles, they may acknowledge that some girls and boys may not want to do things that are typical for their gender identity. At the same time, they are aware that violating gender-role norms can have social costs. Gender segregation persists through childhood. Cross-gender teasing is used to maintain gender boundaries. Another developmental change during middle childhood in some children’s thinking is an increasing awareness of gender-based prejudice and discrimination towards minoritized groups (Brown & Bigler, 2005). Brown and Bigler (2005) identified various factors that affect whether children recognize gender discrimination. First amongst them are cognitive prerequisites, such as an understanding of cultural norms, the ability to make social comparisons, and understanding fairness and equity. These abilities are typically reached by middle childhood. Second, people’s awareness of sexism can also be influenced by individual factors such as their own attitudes. For instance, girls with gender-egalitarian beliefs were more likely to recognize sexism (Brown & Bigler, 2004; Leaper & Brown, 2008). Finally, situational factors can affect children’s likelihood of noticing discrimination. For instance, some children are more likely to notice discrimination directed towards someone else than towards themselves. Also, they are more apt to recognize gender discrimination from persons already known to be prejudiced (Brown & Bigler, 2005). Gender-Typed Behaviours Gender-typed play and interests, as well as affiliations, in gender-segregated peer groups persist throughout middle childhood. Gender-typed play and interests During middle childhood, cisgender girls and boys generally prefer gender-typed play and other interests (Leaper & Bigler, 2018). These trends continue to be more rigid amongst cisgender boys than girls (Farkas & Leaper, 2016). For instance, many girls pursue activities traditionally associated with boys, such as sports and video games. In contrast, it is relatively uncommon to see cisgender boys engage in activities traditionally associated with girls, such as dance and fashion. Gender-segregated peer affiliations Most cisgender girls and boys continue to spend time primarily in same-gender peer groups during middle childhood (Leaper, 2022). On average, boys’ and girls’ gender-segregated peer groups establish somewhat different norms for behaviour (Rose & Rudolph, 2006). For this reason, some researchers have suggested that cisgender girls and boys often construct their own “gender culture” during childhood (Maccoby, 1998). Based on research conducted in several countries, boys’ peer groups were more likely than girls’ peer groups to maintain norms emphasizing dominance, self-reliance, competition, and hiding vulnerability. In contrast, girls’ peer groups were more likely than boys’ peer groups to reinforce norms valuing interpersonal sensitivity, supportiveness, and affection (Bassen & Lamb, 2006; Best & Bush, 2016; Rose & Rudolph, 2006). It is important to add that these gender-typed norms were not seen in all peer groups. During the elementary school years, boys’ and girls’ groups rarely mix. Children themselves enforce gender segregation; this tendency does not seem to be due to adult influences. Although most cisgender children favour same-gender peers during middle childhood, friendly mixed-gender contacts regularly occur in certain contexts (Sroufe et al., 1993; Strough & Covatto, 2002). In private settings, such as the home and in the neighbourhood, play companions may be limited. As a result, girls and boys often play cooperatively with one another in these situations. In more public settings, the implicit convention is that girls and boys can be friendly if they can attribute the reason for this contact to an external cause. For example, this can occur when a teacher assigns mixed-gender groups to work on a class project or when students are waiting in line together at the cafeteria. However, beyond such exceptions, the risk of peer rejection can be high for children who violate the social convention to avoid cross-gender contact (Sroufe et al., 1993). Adolescencen many respects, adolescence (approximately 12 to 18 years of age) is a pivotal point during gender development. First, with the onset of puberty, teens are developing secondary sexual characteristics that make their sex or gender more salient to both themselves and others. Second, this is also a period of exploration when youth are considering their personal identities, gender identities, and sexual identities (see Chapter 11). In addition, adolescents’ gender attitudes may affect the development of relationship intimacy in close friendships and dating (see Chapter 13). Physical Development During adolescence, a series of dramatic bodily transformations are associated with puberty, with the maturation of reproductive organs and secondary sex characteristics. In female adolescents, puberty typically begins with enlargement of the breasts and the general growth spurt in height and weight, followed by the appearance of pubic hair and then menarche (the onset of menstruation). In addition, female adolescents develop the capacity to become pregnant and lactate. In male adolescents, puberty generally starts with the growth of the testes, followed by the appearance of pubic hair, the general growth spurt, increases in muscle mass, growth of the penis, and spermarche (the capacity for ejaculation). For both female and male adolescents, there is considerable variability in physical maturation due to both genetic and environmental factors. Genes affect growth and sexual maturation in large part by influencing the production of hormones, especially growth hormone (secreted by the pituitary gland) and thyroxine (released by the thyroid gland). The influence of environmental factors is particularly evident in the changes in physical development that have occurred over generations. In many Westernized countries today, female adolescents begin menstruating several years earlier than their ancestors did 200 years ago. This change is thought to reflect improvement in nutrition over the generations. In early puberty, females are typically taller than males because of females’ earlier physical maturation. By the end of adolescence, males catch up and surpass females in average height and weight. With biological males’ increases in muscle mass and size beginning in late childhood or early adolescence, the gender gap in physical and motor skills greatly increases. After puberty, average sex differences are very large in strength, speed, and size: most female adolescents cannot run as fast or throw a ball as far as most male adolescents can (Malina & Bouchard, 1991; Thomas & French, 1985). These are amongst the largest average differences in abilities seen between the genders (see Table 15.1). Physical differences in strength, speed, and size, as well as women’s childbearing capacity, may be amongst the most impactful biological sex differences on the organization of gender relations in a society. Social psychologists Wendy Wood and Alice Eagly (2002) argued that greater gender inequalities have occurred in societies when forms of economic subsistence favoured physical strength and disadvantaged nursing and childcare. However, in contemporary industrial-technological societies, physical strength is no longer an advantage for most jobs; and resources such as accessible birth control, employer-supported family leave, and affordable day care can make it possible for women (and men) to maintain their engagement in the workforce. The physical changes typically experienced during puberty are accompanied by psychological and behavioural changes. For example, in some cultures, these changes affect adolescents’ body image—how a person perceives and feels about their physical appearance. A survey of more than 1500 Canadian preadolescents found that roughly half of both the girls and boys were dissatisfied with their bodies, but that the type of dissatisfaction varied across genders: girls were mostly concerned about losing weight; boys, with being more muscular (Dion et al., 2016). Dissatisfaction with body image has long been associated with a host of difficulties, ranging from low self-esteem and depression to eating disorders (Levine & Smolak, 2010). The pervasive sexual objectification of girls in the culture has an especially debilitating effect on many girls (Daniels et al., 2020). A meta-analysis revealed lower average indices of body image amongst girls than boys—with a medium effect size (He et al., 2020; see also Table 15.1). Video: Puberty Concerns with appearance and body dissatisfaction are seen amongst many youth, but especially amongst girls. Another change that accompanies physical maturation is the onset of sexual attraction, which usually begins before the physical process of puberty is complete. According to the recollections of a sample of adults in the United States, sexual attraction is first experienced at about 10 years of age—regardless of sexual orientation (McClintock & Herdt, 1996; see also Chapter 11). Gender-Segregated Peer Affiliations During early adolescence, peer affiliations for most youth remain primarily with members of the same gender (for a review, see Leaper, 2022). However, in many communities, mixed-gender peer groups and friendships become more common during adolescence (Poulin & Pedersen, 2007). These interactions can open the way to romantic relationships amongst heterosexual Canadian youth (Connolly et al., 2004). In some cultural settings, however, there are strict rules regarding mixed-gender contacts, especially as youth enter adolescence. For example, in Orthodox Jewish, Islamic, and Amish societies, girls and boys are separated outside of the home, and any mixed-gender contact must be supervised by family members. Adolescence is also a period of increased intimacy in same-gender friendships. For many girls and boys, increased emotional closeness is often attained through sharing personal feelings and thoughts. On average, higher rates of self-disclosure were seen amongst girls than boys (Rose & Rudolph, 2006; see Table 15.1). However, there is variability amongst boys in the ways they experience and express closeness in friendships. While some boys attain intimacy through shared disclosures with same-gender friends, other boys avoid self-disclosure with same-gender friends because they wish to appear strong (Rogers et al., 2021). Also, many boys seek closeness through shared activities, such as sports (e.g., Mathur & Berndt, 2006). In addition to same-gender friendships, mixed-gender platonic friendships may occur amongst some adolescents (Borowski & Rose, 2021), especially if the peer environment supports these relationships (e.g., Andrews, Cook, & Martin, 2022). Gender-Role Flexibility and Gender Intensification Adolescence is a time that most people explore their personal identities, including their values and beliefs regarding gender roles (e.g., Cooper & Grotevant, 1987). In this process, gender roles might become either more relaxed or more rigid, depending on individual and contextual factors. For some youth, increases in gender-role flexibility occur during late childhood and adolescence as they reject traditional gender roles as social conventions that perpetuate inequality and discrimination (Yu et al., 2017). Hence, they may embrace egalitarian attitudes and consider a broader set of interests. Also, individuals can be flexible about some things while remaining traditional about other matters. For girls and boys, gender-role flexibility will partly depend on social support from family and peers (Kågesten et al., 2016) as well as equal opportunities in society (Wood & Eagly, 2012). Social support (and the absence of rejection) for gender-role flexibility from peers, family, teachers, and others is especially important for gender nonconforming youth (Olson et al., 2016). In many cultures, support for gender-role flexibility is more likely for girls than boys for reasons explained in the earlier section on social identity theory. In many cultures, parents, peers, and teachers are much more accepting of girls who engage in masculine-stereotyped activities than they are of boys who engage in feminine-stereotyped activities. Whereas some adolescents reject traditional gender roles, others internalize them as personal values (Stoddart & Turiel, 1985). As a consequence, concerns with adhering to gender-role expectations may increase for many cisgender adolescents (Galambos, Almeida, & Petersen, 1990; Hill & Lynch, 1983). This gender-role intensification commonly occurs in the context of heterosexual dating when adolescents usually adhere to traditional heterosexual scripts. Examples include expectations that boys or young men will initiate and pay for dates (McCarty & Kelly, 2015; Paynter & Leaper, 2016; Robnett & Leaper, 2013b). Indeed, many heterosexual adolescents and adults who generally endorse gender equality remain traditional in some of their views about heterosexual relationships. In addition to traditional dating scripts, there is a sexual double standard whereby sexual agency is often viewed positively for boys and negatively for girls (Kreager & Staff, 2009; Martinez et al., 2021)—despite the widespread sexualization of girls and women (Daniels et al., 2020). Some evidence suggests that this sexual double standard may be declining (Sagebin Bordini & Sperb, 2013), especially in more gender-egalitarian countries (Endendijk, van Baar, & Deković, 2020). Gender-role intensification during adolescence is also experienced through increases in sexual harassment (Brown et al., 2020; Leaper & Gutierrez, 2023; see also Box 15.3). In Canada, a study of grade 7 and 8 students in Ontario found that 35% to 45% of students reported at least one incidence of sexual harassment during the school year (Schnoll et al., 2015). Several studies have documented how instances of sexual harassment and bullying were more likely directed towards gender nonconforming youth (e.g., boys who are not athletic, girls who were not viewed as pretty or feminine), as well as sexual- and gender-minoritized youth (Hill & Kearl, 2011; Martin-Storey, 2016; Mitchell, Ybarra, & Korchmaros, 2014). When sexual- and gender-minoritized adolescents encounter strong heteronormative and cisgender expectations in their community, they may face stigmatization and corresponding challenges in embracing their sexual or gender identities (Toomey et al., 2010). However, in many schools in Canada today, there are straight-LGBTQ alliances that foster acceptance and support for sexual-minoritized, gender-minoritized, and other gender nonconforming youth (e.g., Poteat et al., 2017).Ambivalent sexist attitudes and traditional gender roles Psychologists Peter Glick and Susan Fiske’s (2001) ambivalent sexism theory addresses the seeming paradox of heterosexual women and men in intimate relationships that are traditionally unequal in power. To explain how both intimacy and dominance can co-occur, the theory distinguishes between hostile sexism (whereby men are dominant and women seeking equality are disparaged) and benevolent sexism (whereby men are supposed to protect women in the context of traditional heterosexual relationships). Although benevolent sexism may seem innocent, Glick and Fiske point out that it helps to perpetuate gender differences in status and power (e.g., women are expected to rely on their male partners for financial support and safety). Both hostile and benevolent sexism often occur together. Thus, during adolescence, rates of sexual harassment (forms of hostile sexism) rise during the same period that traditional heterosexual courtship patterns (forms of benevolent sexism) are common (for a review, see Leaper & Gutierrez, 2023). Furthermore, the endorsements of benevolent and hostile sexism can lead to lowered relationship satisfaction between women and men in heterosexual relationships over time (Hammond & Overall, 2017). Although most research on ambivalent sexism has been conducted with adults, several studies have found these attitudes were commonly endorsed amongst adolescents around the world—even in some of the most gender-egalitarian countries (for a review, see Leaper & Gutierrez, 2023). Adolescents’ endorsements of hostile or benevolent sexism were associated with higher rates of tolerating or perpetrating sexual harassment or sexual violence, prejudicial attitudes towards lesbian and gay people, and support of double standards in heterosexual dating. Also, girls’ endorsement of benevolent sexism was linked to restricted career aspirations and greater involvement in housework