Patterns of interest similarity in adoptive and biological families.

Twin studies have indicated that genetic differences among individuals also contribute to interest and personality differences among them. In this study, 114 biologically related families and 100 adoptive families were administered the Strong-Campbell Interest Inventory. The protocols of parents and their adolescent children (total N = 870) were scored on the six scales of Holland's model of interest styles (Realistic, Investigative, Artistic, Social, Enterprising, Conventional). Biological parent--child correlations ranged from -.13 to +.40, with 15 of the 24 scale correlations achieving significance; only 2 of the adoptive parent--child correlations were significant (range from -.15 to +.25). Biologically related pairs were also significantly more correlated than adoptive pairs for interest profiles. Same-sex biological siblings were more similar to each other than either opposite-sex siblings pairs or parent--child pairs. Pairs of unrelated children in the adoptive families were not too similar either on Holland's scales or the profile analysis.