Adoptions can occur either between related family members, or unrelated individuals. Historically, most adoptions occurred within a family. The most recent data from the U.S. indicates about half of adoptions are currently between related individuals. A common example of this is a "stepparent adoption", where the new partner of a parent may legally adopt a child from the parent's previous relationship. Intra-family adoption can also occur through surrender, as a result of parental death, or when the child cannot otherwise be cared for and a family member agrees to take over.
United States approx 136,000 (2008) 3,978,500 (2015) ≈3 per 100 live births The number of adoptions is reported to be constant since 1987. Since 2000, adoption by type has generally been approximately 15% international adoptions, 40% from government agencies responsible for child welfare, and 45% other, such as voluntary adoptions through private adoption agencies or by stepparents and other family members.
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.
As the idea of institutional care gained acceptance, formal rules appeared about how to place children into families: boys could become apprenticed to an artisan and girls might be married off under the institution's authority. Institutions informally adopted out children as well, a mechanism treated as a way to obtain cheap labor, demonstrated by the fact that when the adopted died, their bodies were returned by the family to the institution for burial.
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.
As a reaction against the bans and hurdles affecting international adoption, scholars Elizabeth Bartholet and Paulo Barrozo claim that every child has a right to a family as a matter of basic human rights. This claim devalues heritage or "cultural" claims and emphasizes the child's existence as a human being rather than a "property" of specific nations or, for example, abusive caregivers.
There are many ways in which the concept of identity can be defined. It is true in all cases that identity construction is an ongoing process of development, change and maintenance of identifying with the self. Research has shown that adolescence is a time of identity progression rather than regression. One's identity tends to lack stability in the beginning years of life but gains a more stable sense in later periods of childhood and adolescence. Typically associated with a time of experimentation, there are endless factors that go into the construction of one's identity. As well as being many factors, there are many types of identities one can associate with. Some categories of identity include gender, sexuality, class, racial and religious, etc. For transracial and international adoptees, tension is generally found in the categories of racial, ethnic and national identification. Because of this, the strength and functionality of family relationships play a huge role in its development and outcome of identity construction. Transracial and transnational adoptees tend to develop feelings of a lack of acceptance because of such racial, ethnic, and cultural differences. Therefore, exposing transracial and transnational adoptees to their "cultures of origin" is important in order to better develop a sense of identity and appreciation for cultural diversity. Identity construction and reconstruction for transnational adoptees the instant they are adopted. For example, based upon specific laws and regulations of the United States, the Child Citizen Act of 2000 makes sure to grant immediate U.S. citizenship to adoptees.
Unlike guardianship or other systems designed for the care of the young, adoption is intended to effect a permanent change in status and as such requires societal recognition, either through legal or religious sanction. Historically, some societies have enacted specific laws governing adoption; where others have tried to achieve adoption through less formal means, notably via contracts that specified inheritance rights and parental responsibilities without an accompanying transfer of filiation. Modern systems of adoption, arising in the 20th century, tend to be governed by comprehensive statutes and regulations.