Behavioral Genetics and Gene–Environment Interaction (7A) - MCAT Psychological and Social Foundations

Study of genetic and environmental contributions to behavior. Examines how genes and environment shape behavioral traits.

Proportion of phenotypic variance due to genetic variance in a population. Measures genetic contribution to trait variation in a population.

$h^2=\frac{V_G}{V_P}$. Genetic variance divided by total phenotypic variance.

Genetic variance does not explain phenotypic variance in that population. All trait variation is due to environmental factors.

They are environment- and population-specific; they do not generalize universally. Heritability changes with different environments and populations.

Multiple genes contribute additively to one trait. Many genes each contribute small effects to one trait.

One gene influences multiple phenotypic traits. Single gene affects multiple seemingly unrelated traits.

Environment-related changes in gene expression without DNA sequence change. Environmental factors alter gene activity patterns.

An individual seeks environments consistent with genetic predispositions. People select environments matching their genetic tendencies.

An individual’s heritable traits evoke specific responses from others. Genetically outgoing children receive more social interaction.

MZ and DZ twins experience equally similar environments relevant to the trait. Assumes environmental similarity is same for MZ and DZ twins.

Monozygotic (MZ) twins. MZ twins share 100% of DNA vs DZ twins' 50%.

Probability that both twins show a trait given that one twin shows it. Measures trait similarity between twin pairs.

Environmental influences that make siblings more similar. Family environment, parenting, and shared experiences.

Population level; it does not measure an individual’s genetic determination. Describes variance in a population, not individual genetics.

All phenotypic variance is explained by genetic variance in that population. All trait variation is due to genetic factors.

Parents provide both genes and environment correlated with those genes. Musical parents give musical genes and musical home environment.

Genetic differences influence exposure to particular environments. Genes affect which environments individuals experience.

Genetic effects on a trait depend on the environment (and vice versa). Same genotype produces different phenotypes in different environments.

Heritability does not apply to individuals; it applies to populations. Describes variance in groups, not individual trait causation.

Observed variation is not explained by genetic variation. All trait differences come from environmental factors.

$h^2=\frac{V_G}{V_P}$. Genetic variance divided by total phenotypic variance.

Proportion of phenotypic variance due to genetic variance in a population. Measures how much genes contribute to trait differences in a group.

Genetic tendencies influence exposure to particular environments. Genes affect which environments individuals experience.

Genotype is genetic makeup; phenotype is expressed trait. Genotype is DNA code; phenotype is observable characteristics.

Separate genetic effects from rearing (shared) environmental effects. Compares adopted children to biological vs. adoptive parents.

Approximately $50%$ of segregating genes shared. Fraternal twins develop from two zygotes, like regular siblings.

Approximately $100%$ of segregating genes shared. Identical twins develop from one zygote, sharing all genes.

Greater MZ than DZ similarity suggests genetic contribution. MZ twins share more genes, so higher similarity implies genetic influence.