Adoption Studies

• Adoption studies are used to test the existence and strength of inherited predispositions.
• Similarities between the adoptee and biological parents can be regarded as estimates of genetic influences.
• Children who are adopted and have biologically criminal parents are more likely to end up as offenders themselves.
• The Swedish adoption study found that children with a history of crime in their family were at higher risk of committing crimes themselves, regardless of whether they grew up with them or not. This suggests that genetics play an important role in criminal behaviour.
• Crowe found that if a biological mother had a criminal record, 50% of the adopted children also had one by the time they were 18. In the control group, only 5% of adopted children had a criminal record by age 18 Regardless of a changed environment, children seemed biologically predisposed to criminality.
• Mednick looked at court convictions and found 14,000 adoptees amongst them. The criminal records of their biological and adoptive parents were then investigated. Many adoptees had criminal biological parents - mainly fathers and sons.