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]
During the same period, the Progressive movement swept the United States with a critical goal of ending the prevailing orphanage system. The culmination of such efforts came with the First White House Conference on the Care of Dependent Children called by President Theodore Roosevelt in 1909,[33] where it was declared that the nuclear family represented "the highest and finest product of civilization" and was best able to serve as primary caretaker for the abandoned and orphaned.[34][35] Anti-institutional forces gathered momentum. As late as 1923, only two percent of children without parental care were in adoptive homes, with the balance in foster arrangements and orphanages. Less than forty years later, nearly one-third were in an adoptive home.[36]

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]
Adopting older children presents other parenting issues.[101] Some children from foster care have histories of maltreatment, such as physical and psychological neglect, physical abuse, and sexual abuse, and are at risk of developing psychiatric problems.[102][103] Such children are at risk of developing a disorganized attachment.[104][105][106] Studies by Cicchetti et al. (1990, 1995) found that 80% of abused and maltreated infants in their sample exhibited disorganized attachment styles.[107][108] Disorganized attachment is associated with a number of developmental problems, including dissociative symptoms,[109] as well as depressive, anxiety, and acting-out symptoms.[110][111] "Attachment is an active process- it can be secure or insecure, maladaptive or productive."[112] In the UK some adoptions fail because the adoptive parents do not get sufficient support to deal with difficult, traumatized children. This is a false economy as local authority care for these children is extremely expensive.[113]
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]
The nobility of the Germanic, Celtic, and Slavic cultures that dominated Europe after the decline of the Roman Empire denounced the practice of adoption.[15] In medieval society, bloodlines were paramount; a ruling dynasty lacking a "natural-born" heir apparent was replaced, a stark contrast to Roman traditions. The evolution of European law reflects this aversion to adoption. English Common Law, for instance, did not permit adoption since it contradicted the customary rules of inheritance. In the same vein, France's Napoleonic Code made adoption difficult, requiring adopters to be over the age of 50, sterile, older than the adopted person by at least 15 years, and to have fostered the adoptee for at least six years.[16] Some adoptions continued to occur, however, but became informal, based on ad hoc contracts. For example, in the year 737, in a charter from the town of Lucca, three adoptees were made heirs to an estate. Like other contemporary arrangements, the agreement stressed the responsibility of the adopted rather than adopter, focusing on the fact that, under the contract, the adoptive father was meant to be cared for in his old age; an idea that is similar to the conceptions of adoption under Roman law.[17]
Other studies provide evidence that adoptive relationships can form along other lines. A study evaluating the level of parental investment indicates strength in adoptive families, suggesting that parents who adopt invest more time in their children than other parents and concludes, "...adoptive parents enrich their children's lives to compensate for the lack of biological ties and the extra challenges of adoption."[94] Another recent study found that adoptive families invested more heavily in their adopted children, for example, by providing further education and financial support. Noting that adoptees seemed to be more likely to experience problems such as drug addiction, the study speculated that adoptive parents might invest more in adoptees not because they favor them, but because they are more likely than genetic children to need the help.[95]

The next stage of adoption's evolution fell to the emerging nation of the United States. Rapid immigration and the American Civil War resulted in unprecedented overcrowding of orphanages and foundling homes in the mid-nineteenth century. Charles Loring Brace, a Protestant minister became appalled by the legions of homeless waifs roaming the streets of New York City. Brace considered the abandoned youth, particularly Catholics, to be the most dangerous element challenging the city's order.[26][27]
Externally focused theories, in contrast, suggest that reunion is a way for adoptees to overcome social stigma. First proposed by Goffman, the theory has four parts: 1) adoptees perceive the absence of biological ties as distinguishing their adoptive family from others, 2) this understanding is strengthened by experiences where non-adoptees suggest adoptive ties are weaker than blood ties, 3) together, these factors engender, in some adoptees, a sense of social exclusion, and 4) these adoptees react by searching for a blood tie that reinforces their membership in the community. The externally focused rationale for reunion suggests adoptees may be well adjusted and happy within their adoptive families, but will search as an attempt to resolve experiences of social stigma.[167]