<P> 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 . </P> <P> 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 . </P> <P> The adoptee population does, however, seem to be more at risk for certain behavioral issues . Researchers from the University of Minnesota studied adolescents who had been adopted and found that adoptees were twice as likely as non-adopted people to suffer from oppositional defiant disorder and attention - deficit / hyperactivity disorder (with an 8% rate in the general population). Suicide risks were also significantly greater than the general population . Swedish researchers found both international and domestic adoptees undertook suicide at much higher rates than non-adopted peers; with international adoptees and female international adoptees, in particular, at highest risk . </P> <P> Nevertheless, work on adult adoptees has found that the additional risks faced by adoptees are largely confined to adolescence . Young adult adoptees were shown to be alike with adults from biological families and scored better than adults raised in alternative family types including single parent and step - families . Moreover, while adult adoptees showed more variability than their non-adopted peers on a range of psychosocial measures, adult adoptees exhibited more similarities than differences with adults who had not been adopted . There have been many cases of remediation or the reversibility of early trauma . For example, in one of the earliest studies conducted, Professor Goldfarb in England concluded that some children adjust well socially and emotionally despite their negative experiences of institutional deprivation in early childhood . Other researchers also found that prolonged institutionalization does not necessarily lead to emotional problems or character defects in all children . This suggests that there will always be some children who fare well, who are resilient, regardless of their experiences in early childhood . Furthermore, much of the research on psychological outcomes for adoptees draws from clinical populations . This suggests that conclusions such that adoptees are more likely to have behavioral problems such as ODD and ADHD may be biased . Since the proportion of adoptees that seek mental health treatment is small, psychological outcomes for adoptees compared to those for the general population are more similar than some researchers propose . </P>

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