Adopted persons increasingly have turned to genetic testing to obtain health information or to search for birth family. The present study investigated psychological factors that may contribute to interest among adoptees and their parents in genetic testing for the adoptee, including adoptees' ethnic identity development, their thoughts or curiosity about birth family (birth family thoughts), and the interaction of these two factors. Data were drawn from the second wave of a longitudinal study, conducted in 2014, on transracially, transnationally adopted Korean American adolescents and their adoptive parents. In a sample of 106 adolescent–parent dyads, 2 adolescents (1.89%) had undergone genetic testing. Among the dyads in which adolescents had not sought genetic testing, 47.12% of adolescents and 43.27% of parents indicated interest in genetic testing for the adolescent adoptee. Adolescents' interest in genetic testing was independent from parents' interest. Neither adolescent psychological adjustment nor physical health was related to interest in genetic testing in either adolescents or parents. Adolescents' birth family thoughts were related to adolescents' interest in genetic testing, but not to parents' interest in genetic testing for their child. This study showed ethnic identity exploration and resolution moderated the relationship between birth family thoughts and adolescents' interest in genetic testing. Results point to the relevance of birth family thoughts and identity development to genetic testing in transnational and transracial adolescent adoptees.