Taken together, these trends resulted in a new American model for adoption. Following its Roman predecessor, Americans severed the rights of the original parents while making adopters the new parents in the eyes of the law. Two innovations were added: 1) adoption was meant to ensure the "best interests of the child;" the seeds of this idea can be traced to the first American adoption law in Massachusetts,[16][23] and 2) adoption became infused with secrecy, eventually resulting in the sealing of adoption and original birth records by 1945. The origin of the move toward secrecy began with Charles Loring Brace who introduced it to prevent children from the Orphan Trains from returning to or being reclaimed by their parents. Brace feared the impact of the parents' poverty, in general, and their Catholic religion, in particular, on the youth. This tradition of secrecy was carried on by the later Progressive reformers when drafting of American laws.[44]
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.[114]
The American model of adoption eventually proliferated globally. England and Wales established their first formal adoption law in 1926. The Netherlands passed its law in 1956. Sweden made adoptees full members of the family in 1959. West Germany enacted its first laws in 1977.[49] Additionally, the Asian powers opened their orphanage systems to adoption, influenced as they were by Western ideas following colonial rule and military occupation.[50] In France, local public institutions accredit candidates for adoption, who can then contact orphanages abroad, or ask for the support of NGOs. The system does not involve fees, but gives considerable power to social workers whose decisions may restrict adoption to standardized families (middle-age, medium to high income, heterosexual, Caucasian).[51]
The research literature states adoptees give four reasons for desiring reunion: 1) they wish for a more complete genealogy, 2) they are curious about events leading to their conception, birth, and relinquishment, 3) they hope to pass on information to their children, and 4) they have a need for a detailed biological background, including medical information. It is speculated by adoption researchers, however, that the reasons given are incomplete: although such information could be communicated by a third-party, interviews with adoptees, who sought reunion, found they expressed a need to actually meet biological relations.[167]

Attitudes and laws regarding adoption vary greatly. Whereas all cultures make arrangements whereby children whose birth parents are unavailable to rear them can be brought up by others, not all cultures have the concept of adoption, that is treating unrelated children as equivalent to biological children of the adoptive parents. Under Islamic Law, for example, adopted children must keep their original surname to be identified with blood relations,[194] and, traditionally, women wear a hijab in the presence of males in their adoptive households. In Egypt, these cultural distinctions have led to making adoption illegal.[195]

The number of adoptions in the United States peaked in 1970.[45] It is uncertain what caused the subsequent decline. Likely contributing factors in the 1960s and 1970s include a decline in the fertility rate, associated with the introduction of the pill, the completion of legalization of artificial birth control methods, the introduction of federal funding to make family planning services available to the young and low income, and the legalization of abortion. In addition, the years of the late 1960s and early 1970s saw a dramatic change in society's view of illegitimacy and in the legal rights[46] of those born outside of wedlock. In response, family preservation efforts grew[47] so that few children born out of wedlock today are adopted. Ironically, adoption is far more visible and discussed in society today, yet it is less common.[48]

Reform and family preservation efforts have also been strongly associated with the perceived misuse of adoption. In some cases, parents' rights have been terminated when their ethnic or socio-economic group has been deemed unfit by society. Some of these practices were generally accepted but have later been considered abusive; others were uncontroversially reprehensible.
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.[127] 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.[128] 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.[128]
International adoption: involves the placing of a child for adoption outside that child's country of birth. This can occur through both public and private agencies. In some countries, such as Sweden, these adoptions account for the majority of cases (see above Table). The U.S. example, however, indicates there is wide variation by country since adoptions from abroad account for less than 15% of its cases.[83] More than 60,000 Russian children have been adopted in the United States since 1992,[85] and a similar number of Chinese children were adopted from 1995 to 2005.[86] The laws of different countries vary in their willingness to allow international adoptions. Recognizing the difficulties and challenges associated with international adoption, and in an effort to protect those involved from the corruption and exploitation which sometimes accompanies it, the Hague Conference on Private International Law developed the Hague Adoption Convention, which came into force on 1 May 1995 and has been ratified by 85 countries as of November 2011.[87]
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.