At the end of a designated term of (voluntary) co-habitation, as witnessed by the public, the adoption is then considered binding, in some courts of law, even though not initially sanctioned by the court. The particular terms of a common-law adoption are defined by each legal jurisdiction. For example, the U.S. state of California recognizes common law relationships after co-habitation of 2 years. The practice is called "private fostering" in Britain. Disruption and dissolution
Although adoption is often described as forming a "forever" family, the relationship can be ended at any time. The legal termination of an adoption is called disruption. In U.S. terminology, adoptions are disrupted if they are ended before being finalized, and they are dissolved if the relationship is ended afterwards. It may also be called a failed adoption. After legal finalization, the disruption process is usually initiated by adoptive parents via a court petition and is analogous to divorce proceedings. It is a legal avenue unique to adoptive parents as disruption/dissolution does not apply to biological kin, although biological family members are sometimes disowned or abandoned.Ad hoc studies performed in the U.S., however, suggest that between 10 and 25 percent of adoptions through the child welfare system (e.g., excluding babies adopted from other countries or step-parents adopting their stepchildren) disrupt before they are legally finalized and from 1 to 10 percent are dissolved after legal finalization.
Danish and American researchers conducting studies on the genetic contribution to body mass index found correlations between an adoptees 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.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 develop oppositional defiant disorder (ODD) and attention deficit hyperactivity disorder (ADHD), 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.Nevertheless, work on adult adoptees has found that the additional risks faced by adoptees are largely confined to adolescence.