Developmental Psychology Notes - Chapter 2: Genetic and Environmental Foundations

Developmental Psychology (PSCH 320)

Dr. Spizzirri, UIC, 1-21-2025

Agenda

• Housekeeping: Remember to read the textbook.
• UIC library resources.
• Chapter 2 slides: Genetic and Environmental Foundations

Learning Objectives

• Describe the influence of nature and nurture on development.
• Explain how genetics influences development.
• Explain how the environment influences development.
• Describe how twin and adoptee studies help researchers understand nature vs. nurture.

Genotype and Phenotype

• Genotype: An individual’s unique genetic information.
• Phenotype: An individual’s directly observable characteristics.

Genetic Foundations

• Chromosomes: Structures that store and transmit genetic information.
• DNA: The substance of which genes and chromosomes are made.
• Gene: A segment of DNA located along the chromosomes.

Autosomes, Sex Chromosomes, and Sex Cells

• Autosomes: 22 matching pairs of chromosomes.
• Sex Chromosomes: 23rd pair of chromosomes (XX = female, XY = male).
• Gametes: Sex cells (sperm and ovum).
• Zygote: Formed when sperm and ovum unite.

Twins

• Monozygotic Twins (Identical): One zygote that divides into two individuals.
• Dizygotic Twins (Fraternal): Two zygotes, or fertilized ova.

Alleles

• Two forms of the same gene, one inherited from each parent, located at the same place on both chromosomes in a pair.
  • Homozygous: Both alleles are alike.
  • Heterozygous: Alleles are different.

Dominant-Recessive Inheritance

• Only the dominant allele affects the child’s characteristics.
• The recessive allele can be passed to children.
• Many serious disabilities and diseases result from recessive alleles.

Example of Dominant-Recessive Inheritance: Cystic Fibrosis

• Autosomal recessive inheritance.
• If both parents are carriers (Cc), the probabilities are:
  • 25% chance of the child being affected (cc).
  • 75% chance cystic fibrosis not expressed (CC or Cc)

Incomplete Dominance

• Both alleles are expressed in the phenotype.
• Results in a combined trait or an intermediate between the two.
• Example: Sickle cell anemia.

X-Linked Inheritance

• A harmful allele is carried on the X chromosome.
• Males are more likely to be affected because the shorter Y chromosome lacks corresponding genes to override those on the X.
• Example: Hemophilia.

X-Linked Recessive Inheritance

• Affected father passes the mutated gene to daughters, who become carriers.
• Carrier mother has a 50% chance of passing the mutated gene to her sons, who will be affected, and a 50% chance of passing it to her daughters, who will become carriers.

Mutation

• A sudden, permanent change in a DNA segment.
• Can occur spontaneously or be caused by hazardous environmental agents.
• Types of mutations: Germline and Somatic.

Polygenic Inheritance

• Many genes affect each characteristic that varies among people.
• Examples: height, weight, intelligence, personality.

Chromosomal Abnormalities

• Down Syndrome: Results when the 21st chromosome pair fails to separate during meiosis.
• Sex Chromosome Abnormalities: Caused by problems with the X or Y chromosome; often not recognized until adolescence.

Risk of Down Syndrome by Maternal Age

• Risk increases significantly with maternal age.

Reproductive Choices

• Genetic counseling.
• Reproductive technologies.
• Prenatal diagnosis and fetal medicine.
• Adoption.

Genetic Counseling

• Helps couples assess the risk of hereditary disorders and choose the best course of action.
• Individuals likely to seek genetic counseling:
  • Couples who have had difficulties bearing children.
  • Those with known genetic problems.
  • Women over 35.

Social Issues: Health - Pros and Cons of Reproductive Technologies

• Donor insemination.
• In vitro fertilization.
• Surrogate motherhood.
• Ethical concerns:
  • Postmenopausal childbearing.
  • Selection of desired characteristics; “designer babies”.
  • Exploitation of financially needy women.

Genetic Engineering

• Purpose: to correct hereditary defects.
• Human Genome Project:
  • Mapped sequence of all human DNA base pairs.
  • Working on identifying all genes and their functions.
  • Exploring new treatments, such as gene therapy and proteomics.

Adoption

• Adoptees may have more learning and emotional difficulties due to:
  • Genetic predispositions.
  • Stress of the biological mother.
  • History of conflict-ridden family relationships.
  • Adoptive parents and children being less alike.
• With sensitive parenting, most adoptees fare well.

Environmental Contexts for Development

• Family.
• Socioeconomic status (SES).
• Poverty/affluence.
• Neighborhoods.
• Schools.
• Cultural context.

Family Influences on Development

• Direct: Two-person relationships (e.g., parent-child, sibling relationships, marital spouse).
• Indirect: Third parties (e.g., a healthy marriage fosters effective coparenting).
• Adapting to changes within and outside the family (e.g., birth of a baby).

Socioeconomic Status (SES)

• Index that combines three related variables:
  • Years of education.
  • Prestige of one’s job and skill it requires.
  • Income.
• The first two measure social status; the last measures economic status.

Socioeconomic Status and Family Functioning

• SES is linked to:
  • Timing of marriage and parenthood.
  • Family size.
  • Child-rearing values and expectations.
  • Communication and discipline styles.
  • Parents’ education and economic security.
  • Children’s cognitive and social development.

Poverty

• 21% of U.S. children live in poverty.
• Rates are higher for children of parents under age 25, ethnic minorities, and single mothers.
• Risks of poverty:
  • Lifelong poor physical health.
  • Poor cognitive development and academic achievement.
  • Mental illness.
  • Impulsivity, aggression, and antisocial behavior.
  • Hostile family interactions.

Affluence

• Risks of affluence:
  • Poor academic achievement.
  • Alcohol and drug use.
  • Delinquency.
  • Anxiety and depression.
• Unavailable parents:
  • Lack emotional closeness and supervision.
  • Make excessive demands for achievement.

Relationship of Regularly Eating Dinner with Parents to Affluent Youths’ Adjustment Problems

• Regular family dinners are associated with fewer adjustment problems in affluent youth.

Neighborhood

• Offers resources and social ties that promote development.
• Greater impact on economically disadvantaged.
• In-school and after-school programs for low-income children show improved:
  • Academic achievement.
  • Social adjustment.
  • Family functioning and child-rearing.

Schools

• Complex social systems that affect many aspects of development.
• Achieving well in elementary and secondary school is crucial to success in college.
• Children in low-SES neighborhoods are likely to experience poorer quality education.
• Early intervention makes a difference!
• Parental involvement aids academic achievement.

Cultural Context

• Culture shapes all aspects of daily life.
• U.S. culture emphasizes independence, self-reliance, and family privacy.
• Subcultures have beliefs and customs that differ from the larger culture.
  • Example: Ethnic minority groups’ cooperative family structures foster resilience and enhance child-rearing.

Cultural Influences Example: The African-American Extended Family

• Benefits of the African-American extended family:
  • Family members help with child-rearing.
  • Strengthens family bonds.
  • Transmits culture and heritage.
  • Improves children’s school performance and social skills.
  • Reduces stress of poverty and single parenthood, if present.
  • Adolescent mothers are more likely to complete high school and get a job.

Collectivism vs. Individualism

• Collectivism:
  • Stress group goals over individual goals.
  • Value interdependent qualities: responsibility to others, social harmony, collaborative endeavors.
• Individualism:
  • Primarily concerned with own personal needs.
  • Value independence: personal achievement, exploration, and choice in relationships.

U.S. Public Policy Shortcomings

• Children and youth:
  • Lack of affordable health insurance and childcare.
  • Weak enforcement of child support payments.
  • High school dropout rates.
• Older adults:
  • Limited funding for social services.
  • Social Security minimum is below the poverty line.
• Advocacy groups and research help improve policy.

Behavioral Genetics

• Explores contributions of nature and nurture to the diversity of human traits and abilities.
• Limited to investigating the impact of heredity on complex characteristics indirectly.

Heritability Estimates

• Measure the extent to which individual differences in complex traits are due to heredity.
• Obtained from kinship studies (e.g., comparisons of twins or adoptees and their biological parents).
• Estimates range from 0 to 1.00.
  • 0.5 suggests heredity explains half the trait’s variation.
• Limitations: may not represent the population; can be misapplied; limited usefulness.

Gene-Environment Interaction

• Individuals respond differently to the same environment because of their genetic makeup.
• Similar responses can result from different gene-environment combinations.
  • Example: children with different environmental enrichment produce the same intelligence test scores.

Illustration of Gene-Environment Interaction

• Different children respond differently to environmental quality based on their genetic predisposition.

Gene-Environment Correlation

• Our genes influence the environments to which we are exposed.
  • Passive correlation.
  • Evocative correlation.
  • Active correlation: niche-picking.

Epigenesis

• Development resulting from ongoing, bidirectional exchanges:
  • Genes affect behavior and experiences.
  • Behavior and experiences affect gene expression.
• Epigenetics studies how the environment alters gene expression (e.g., methylation).

Epigenesis Example: The Tutsi Genocide and Epigenetic Transmission of Maternal Stress to Children

• Exposure to extreme adversity increases methylation of a gene integral to stress-hormone regulation.
• Tutsi mothers pregnant during the genocide and their children were tested 18 years later:
  • Both had significantly lower stress-hormone levels.
  • Long-lasting effects were evident in serious psychological disorders.
• Prenatal exposure to severe maternal stress can induce epigenetic changes through methylation.