Module 11 Review

REVIEW Behavior Genetics: Predicting Individual Differences

LEARNING OBJECTIVES

RETRIEVAL PRACTICE Take a moment to answer each of these Learning Objective Questions (repeated here from within this section). Then click the 'show answer' button to check your answers. Research suggests that trying to answer these questions on your own will improve your long-term retention (McDaniel et al., 2009).

11-1 What are chromosomes, DNA, genes, and the human genome? How do behavior geneticists explain our individual differences?

Genes are the biochemical units of heredity that make up chromosomes, the threadlike coils of DNA. When genes are “turned on” (expressed), they provide the code for creating the proteins that form our body’s building blocks. Most human traits are influenced by many genes acting together. The human genome is the shared genetic profile that distinguishes humans from other species, consisting at an individual level of all the genetic material in an organism’s chromosomes. Behavior geneticists study the relative power and limits of genetic and environmental influences on behavior.

11-2 How do twin and adoption studies help us understand the effects and interactions of nature and nurture?

Studies of identical (monozygotic) twins versus fraternal (dizygotic) twins, separated twins, and biological versus adoptive relatives allow researchers to tease apart the influences of heredity and environment. Research studies on separated identical twins maintain the same genes while testing the effects of different home environments. Studies of adoptive families let researchers maintain the same home environment while studying the effects of genetic differences. Heritable individual differences (in traits such as height and weight) do not necessarily explain gender or ethnic group differences. Shared family environments have little effect on personality.

11-3 What have psychologists learned about temperament?

The stability of temperament, a person’s characteristic emotional reactivity and intensity, from the first weeks of life suggests a genetic predisposition. The genetic effect appears in physiological differences such as heart rate and nervous system reactivity.

11-4 What is heritability, and how does it relate to individuals and groups?

Heritability describes the extent to which variation among members of a group can be attributed to genes. Heritable individual differences (in traits such as height or intelligence) need not imply heritable group differences. Genes mostly explain why some people are taller than others, but not why people are taller today than they were a century ago.

11-5 How is molecular genetics research changing our understanding of the effects of nature and nurture?

Molecular genetics research on structure and function of genes is building new understandings of how teams of genes influence many human traits. One goal of molecular behavior genetics, the study of how the structure and function of genes interact with our environment to influence behavior, is to find some of the many genes that together orchestrate complex traits (such as body weight, sexual orientation, and impulsivity). Environments can trigger or block genetic expression. The field of epigenetics studies the influences on gene expression that occur without changes in DNA.

11-6 What are some benefits and risks of prenatal genetic testing?

Genetic tests can now reveal at-risk populations for dozens of diseases, and the search is on to discover the markers of genetically influenced disorders. But prenatal screening poses ethical dilemmas. For example, testing for an offspring’s sex has enabled selective abortions, which in some cultures has resulted in millions more male births. And future screening for vulnerability to psychological disorders could deprive the world of great talents. (Handel, van Gogh, Churchill, Lincoln, Tolstoy, and Dickinson were all troubled people, for example.)

TERMS AND CONCEPTS TO REMEMBER

RETRIEVAL PRACTICE Match each of the terms on the left with its definition on the right. Click on the term first and then click on the matching definition. As you match them correctly they will move to the bottom of the activity.

Question

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