Professor Kahn is an expert in behavior genetics. Her research team primarily conducts family studies to compare people who live together and share varying degrees of relatedness. Describe the two types of family studies that Professor Kahn most likely uses in her research, including what these studies tell about genetic and environmental influences on behavior.

Question

What will be an ideal response?

Answer 1

Two kinds of family studies are common: twin studies and adoption studies. Twin studies compare identical and fraternal twins to estimate how much of a trait or behavior is attributable to genes. If genes affect the attribute, identical twins should be more similar than fraternal twins because identical twins share 100% of their genes whereas fraternal twins share about only 50%. Adoption studies on the other hand, compare the degree of similarity between adopted children and their biological parents whose genes they share (50%) and their adoptive parents with whom they share no genes. If the adopted children share similarities with their biological parents, even though they were not raised by them, it suggests that the similarities are genetic. Adoption studies also shed light on the extent to which attributes and behaviors are influenced by the environment. For example, the degree to which two genetically unrelated adopted children reared together are similar speaks to the role of environment. Comparisons of identical twins reared in the same home with those reared in different environments can also illustrate environmental contributions to phenotypes. If identical twins reared together are more similar than those reared apart, an environmental influence can be inferred.