Chapter 3 - Nature, Nurture, and Human Diversity

members of the human family differ in personality, interests, culture, and family background

Twin Studies

Comparisons of identical twins, who are genetic clones, and fraternal twins, who develop from separate eggs, help behaviour geneticists determine the effects of heredity and environment
Research findings show that identical twins are much more similar than fraternal twins in abilities, personality, and even interest
The discovery that identical twins separated at birth show remarkable similarities also suggest genetic influence

an infant’s temperament includes inborn emotional excitability. from the first weeks of life, some babies are more relaxed and cheerful, while others are more tense and irritable
compared to fraternal twins, identical twins have more similar temperament

we are all the products of interactions between our genetic predispositions and our surrounding environments
a baby who is genetically predisposed to be social and easygoing may, in contrast to one who is less so, attract more affectionate and stimulating care and thus develop into a warmer, more outgoing person

at extremes, for example, in the abused become abusive and in loved, but firmly handled children, who become self-confident and socially competent
also reflected in children’s political attitudes, religious beliefs, and personal manners

parental and peer influence are complementary
parents are more influential when it comes to education, discipline, responsibility, orderliness, charitableness, and interacting with authority
peers are more important for learning cooperation, for finding the road to popularity, and for inventing styles of interaction among people of the same age

individualist cultures value personal achievement and fulfillment as well as individual rights and liberties
collectivist cultures value groups goals and solidarity

males and females are similar in genetic makeup as well as levels of intelligence, vocabulary, and happiness
females are more vulnerable to depression, anxiety, and eating disorders
males are more likely to commit suicide, suffer alcoholism, be autistic, color-blind, hyper-active as children, and antisocial personalities as adults

men are perceived as more dominant, forceful, and independent, while women are viewed as more deferential, nurturing, and affiliating
leadership tends to go to males. men are more likely to tale assertively, to interrupt, to initiate touching, to smile less, and to stare

gender roles - our expectations about the way men and women behave - vary across cultures and time
in nomadic societies of food-gathering people, there is little division of labour by sex. thus, boys and girls receive much the same upbringing
even among industrialized countries, gender roles vary greatly, for example, in the expectation that life will be more satisfying when both spouses work and share childcare
social learning theory assumes that children learn gender-linked behaviour by observing and imitating significant others and by being rewarded and punished