Adoption as a natural experiment.

Adoption provides a unique opportunity for the study of child development. Because adopted children are raised in families in which they have no genetic relationship with their parents, and possibly none with their siblings, they provide a rare opportunity to study the relative importance of genetic, shared environmental, and nonshared environmental influences on the development of child characteristics and behaviors. Because children are adopted from a variety of circumstances and at a wide range of ages, studies of adopted children and their families provide researchers the opportunity to examine the short- and long-term influences of a wide range of environments on children's development. Because children are adopted into homes with a range of characteristics (e.g., multiracial homes), adoption provides the opportunity to study the range of influences of these homes on child development. Adoption research that focuses on each of these areas is reviewed in this article. We present conclusions about the value of adoption in psychological research and some reasons why many psychologists ignore the opportunities presented by studying adoptive families, as well as potential useful directions for future research with adopted children and their families.