Adoption studies typically compare pairs of persons, e.g., adopted child and adoptive mother or adopted child and biological mother, to assess genetic and environmental influences on behavior.[1] These studies are one of the classic research methods of behavioral genetics. The method is used alongside twin studies to identify the roles of genetics and environmental variables that impact intelligence, and behavioral disorders.[2]
Adoption studies differ from twin studies in that adoption studies do not necessarily need to use twins; instead, they compare the traits of children to their parents, whether those are the adoptive parents or biological parents.[1]