The investigation of individuals raised by adoptive parents to disentangle the contributions of genetic and environmental factors to specific traits or behaviors is a research methodology employed within behavioral genetics and developmental science. These investigations compare adopted children to both their biological and adoptive parents. For instance, researchers might compare the IQ scores of adopted children to those of their biological parents (representing genetic influence) and their adoptive parents (representing environmental influence) to assess the heritability of intelligence.
This methodology offers unique insights unattainable through studies of traditional nuclear families. Because adopted individuals are raised by parents to whom they are not genetically related, any similarities between the child and the adoptive parents are more likely attributable to environmental factors, such as parenting style or socioeconomic status. Conversely, similarities between the adopted child and their biological parents are suggestive of genetic influence. Historically, such investigations have been pivotal in understanding the relative contributions of nature versus nurture across a range of characteristics, from personality traits to the development of certain mental health conditions. They contribute significantly to the understanding of etiology, developmental trajectories, and risk factors.
