process—it can be secure or insecure, maladaptive or productive." In the U.K., some adoptions fail because the adoptive parents do not get sufficient support to deal with difficult, traumatized children. This is a false economy as local authority care for these children is extremely expensive. Concerning developmental milestones, studies from the Colorado Adoption Project examined genetic influences on adoptee maturation, concluding that cognitive abilities of adoptees reflect those of their adoptive parents in early childhood but show little similarity by adolescence, resembling instead those of their biological parents and to the same extent as peers in non-adoptive families. Similar mechanisms appear to be at work in the physical development of adoptees. Danish and American researchers conducting studies on the genetic contribution to body mass index found correlations between an adoptee's weight class and his biological parents' BMI while finding no relationship with the adoptive family environment. Moreover, about one-half of inter-individual differences were due to individual non-shared influences. These differences in development appear to play out in the way young adoptees deal with major life events. In the case of parental divorce, adoptees have been found to respond differently from children who have not been adopted. While the general population experienced more behavioral problems, substance use, lower school achievement, and impaired social competence after parental divorce, the adoptee population appeared to be unaffected in terms of their outside relationships, specifically in their school or social abilities. Effects on the original parents Several factors affect the decision to release or raise the child. White adolescents tend to give up their babies to non-relatives, whereas black adolescents are more likely to receive support from their own community in raising the child and also in the form of informal adoption by relatives. Studies by Leynes and by Festinger and Young, Berkman, and Rehr found that, for pregnant adolescents, the decision to release the child for adoption depended on the attitude toward adoption held by the adolescent's mother. Another study found that pregnant adolescents whose mothers had a higher level of education were more likely to release their babies for adoption. Research suggests that women who choose to release their babies for adoption are more likely to be younger, enrolled in school, and have lived in a two-parent household at age 10, than those who kept and raised their babies. There is limited research on the consequences of adoption for the original parents, and