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." 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.
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, 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.
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.
Open records: Movements to unseal adoption records for adopted citizens proliferated along with increased acceptance of illegitimacy. In the United States, Jean Paton founded Orphan Voyage in 1954, and Florence Fisher founded the Adoptees' Liberty Movement Association (ALMA) in 1971, calling sealed records "an affront to human dignity.". While in 1975, Emma May Vilardi created the first mutual-consent registry, the International Soundex Reunion Registry (ISRR), allowing those separated by adoption to locate one another. and Lee Campbell and other birthmothers established CUB (Concerned United Birthparents). Similar ideas were taking hold globally with grass-roots organizations like Parent Finders in Canada and Jigsaw in Australia. In 1975, England and Wales opened records on moral grounds.
Open adoption allows identifying information to be communicated between adoptive and biological parents and, perhaps, interaction between kin and the adopted person. Open adoption can be an informal arrangement subject to termination by adoptive parents who have sole custody over the child. In some jurisdictions, the biological and adoptive parents may enter into a legally enforceable and binding agreement concerning visitation, exchange of information, or other interaction regarding the child. As of February 2009, 24 U.S. states allowed legally enforceable open adoption contract agreements to be included in the adoption finalization.
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, 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.
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."