Psychologists' findings regarding the importance of early mother-infant bonding created some concern about whether parents who adopt older infants or toddlers after birth have missed some crucial period for the child's development. However, research on The Mental and Social Life of Babies suggested that the "parent-infant system," rather than a bond between biologically related individuals, is an evolved fit between innate behavior patterns of all human infants and equally evolved responses of human adults to those infant behaviors. Thus nature "ensures some initial flexibility with respect to the particular adults who take on the parental role."[96]
Family preservation: As concerns over illegitimacy began to decline in the early 1970s, social-welfare agencies began to emphasize that, if possible, mothers and children should be kept together.[156] In the U.S., this was clearly illustrated by the shift in policy of the New York Foundling Home, an adoption-institution that is among the country's oldest and one that had pioneered sealed records. It established three new principles including "to prevent placements of children...," reflecting the belief that children would be better served by staying with their biological families, a striking shift in policy that remains in force today.[157]
The research says that the dysfunction, untruths and evasiveness that can be present in adoptive families not only makes identity formation impossible, but also directly works against it. What effect on identity formation is present if the adoptee knows they are adopted but has no information about their biological parents? Silverstein and Kaplan's research states that adoptees lacking medical, genetic, religious, and historical information are plagued by questions such as "Who am I?" "Why was I born?" "What is my purpose?" This lack of identity may lead adoptees, particularly in adolescent years, to seek out ways to belong in a more extreme fashion than many of their non-adopted peers. Adolescent adoptees are overrepresented among those who join sub-cultures, run away, become pregnant, or totally reject their families.[133][134]
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]
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.
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.[115][116]
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 can be disowned or abandoned.[91]

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.[19] 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.[20]
By 1979, representatives of 32 organizations from 33 states, Canada and Mexico gathered in Washington, DC to establish the American Adoption Congress (AAC) passing a unanimous resolution: "Open Records complete with all identifying information for all members of the adoption triad, birthparents, adoptive parents and adoptee at the adoptee's age of majority (18 or 19, depending on state) or earlier if all members of the triad agree."[161] Later years saw the evolution of more militant organizations such as Bastard Nation (founded in 1996), groups that helped overturn sealed records in Alabama, Delaware, New Hampshire, Oregon, Tennessee, and Maine.[162][163] Simultaneously, groups such as Origins USA (founded in 1997) started to actively speak about family preservation and the rights of mothers.[164] The intellectual tone of these recent reform movements was influenced by the publishing of The Primal Wound by Nancy Verrier. "Primal wound" is described as the "devastation which the infant feels because of separation from its birth mother. It is the deep and consequential feeling of abandonment which the baby adoptee feels after the adoption and which may continue for the rest of his life."[153]

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.[117]

Some adoptees reject the idea of reunion. It is unclear, though, what differentiates adoptees who search from those who do not. One paper summarizes the research, stating, "...attempts to draw distinctions between the searcher and non-searcher are no more conclusive or generalizable than attempts to substantiate...differences between adoptees and nonadoptees."[169]
Nevertheless, some indication of the level of search interest by adoptees can be gleaned from the case of England and Wales which opened adoptees' birth records in 1975. The UK Office for National Statistics has projected that 33% of all adoptees would eventually request a copy of their original birth records, exceeding original forecasts made in 1975 when it was believed that only a small fraction of the adoptee population would request their records. The projection is known to underestimate the true search rate, however, since many adoptees of the era get their birth records by other means.[166]
Bloodhounds are champion sniffers, but how do all of those flopping folds and jiggling jowls function? Meet the dogs who smell with their ears! Bloodhounds are champion sniffers — even by dog standards. Although every dog is certainly greater than the sum of its parts, there is some truth to the affectionate description of Bloodhounds as “noses with dogs attached.” …
Adoption practices have changed significantly over the course of the 20th century, with each new movement labeled, in some way, as reform.[152] Beginning in the 1970s, efforts to improve adoption became associated with opening records and encouraging family preservation. These ideas arose from suggestions that the secrecy inherent in modern adoption may influence the process of forming an identity,[153][154] create confusion regarding genealogy,[155] and provide little in the way of medical history.
Other ancient civilizations, notably India and China, used some form of adoption as well. Evidence suggests the goal of this practice was to ensure the continuity of cultural and religious practices; in contrast to the Western idea of extending family lines. In ancient India, secondary sonship, clearly denounced by the Rigveda,[12] continued, in a limited and highly ritualistic form, so that an adopter might have the necessary funerary rites performed by a son.[13] China had a similar idea of adoption with males adopted solely to perform the duties of ancestor worship.[14]
Adoption practices have changed significantly over the course of the 20th century, with each new movement labeled, in some way, as reform.[152] Beginning in the 1970s, efforts to improve adoption became associated with opening records and encouraging family preservation. These ideas arose from suggestions that the secrecy inherent in modern adoption may influence the process of forming an identity,[153][154] create confusion regarding genealogy,[155] and provide little in the way of medical history.
In sum, reunions can bring a variety of issues for adoptees and parents. Nevertheless, most reunion results appear to be positive. In the largest study to date (based on the responses of 1,007 adoptees and relinquishing parents), 90% responded that reunion was a beneficial experience. This does not, however, imply ongoing relationships were formed between adoptee and parent nor that this was the goal.[170]
The practice of closed adoption (aka confidential or secret adoption),[74] which has not been the norm for most of modern history,[75] seals all identifying information, maintaining it as secret and preventing disclosure of the adoptive parents', biological kins', and adoptees' identities. Nevertheless, closed adoption may allow the transmittal of non-identifying information such as medical history and religious and ethnic background.[76] Today, as a result of safe haven laws passed by some U.S. states, secret adoption is seeing renewed influence. In so-called "safe-haven" states, infants can be left, anonymously, at hospitals, fire departments, or police stations within a few days of birth, a practice criticized by some adoption advocacy organizations as being retrograde and dangerous.[77]