Markedly different from the modern period, ancient adoption practices put emphasis on the political and economic interests of the adopter,[4] providing a legal tool that strengthened political ties between wealthy families and created male heirs to manage estates.[5][6] The use of adoption by the aristocracy is well documented; many of Rome's emperors were adopted sons.[6] Adrogation was a kind of Roman adoption which required the adrogator to be at least 60 years old.

Europe's cultural makeover marked a period of significant innovation for adoption. Without support from the nobility, the practice gradually shifted toward abandoned children. Abandonment levels rose with the fall of the empire and many of the foundlings were left on the doorstep of the Church.[18] Initially, the clergy reacted by drafting rules to govern the exposing, selling, and rearing of abandoned children. The Church's innovation, however, was the practice of oblation, whereby children were dedicated to lay life within monastic institutions and reared within a monastery. This created the first system in European history in which abandoned children did not have legal, social, or moral disadvantages. As a result, many of Europe's abandoned and orphaned children became alumni of the Church, which in turn took the role of adopter. Oblation marks the beginning of a shift toward institutionalization, eventually bringing about the establishment of the foundling hospital and orphanage.[18]
Infertility is the main reason parents seek to adopt children they are not related to. One study shows this accounted for 80% of unrelated infant adoptions and half of adoptions through foster care.[79] Estimates suggest that 11–24% of Americans who cannot conceive or carry to term attempt to build a family through adoption, and that the overall rate of ever-married American women who adopt is about 1.4%.[80][81] Other reasons people adopt are numerous although not well documented. These may include wanting to cement a new family following divorce or death of one parent, compassion motivated by religious or philosophical conviction, to avoid contributing to overpopulation out of the belief that it is more responsible to care for otherwise parent-less children than to reproduce, to ensure that inheritable diseases (e.g., Tay–Sachs disease) are not passed on, and health concerns relating to pregnancy and childbirth. Although there are a range of possible reasons, the most recent study of experiences of women who adopt suggests they are most likely to be 40–44 years of age, currently married, have impaired fertility, and childless.[82]

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]
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]
Who are the children who wait? The children who wait are the survivors of abuse and neglect. They are school aged children, siblings, children of color and children with disabilities. Each of them waits for adoption and there are more than 114,000 of them across the country. These children live in a series of foster and group homes for an average of three years. There they wait while they hope for the stability of an adoptive family.

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] 

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]
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]
Adoption is the legal process through which a child joins a family different from his or her birth parents. Adoption is a permanent, lifelong commitment to a child. In CPS cases, adoption becomes an option if CPS and the child's birth parents cannot resolve issues that made it unsafe for the child to live at home. Then, CPS may ask the court to end the parents' rights to the child and place the child with another family permanently. A child can also become legally free for adoption if both birth parents agree to give up their parental rights.
Family plays a vital role in identity formation. This is not only true in childhood but also in adolescence. Identity (gender/sexual/ethnic/religious/family) is still forming during adolescence and family holds a vital key to this. The research seems to be unanimous; a stable, secure, loving, honest and supportive family in which all members feel safe to explore their identity is necessary for the formation of a sound identity. Transracial and International adoptions are some factors that play a significant role in the identity construction of adoptees. Many tensions arise from relationships built between the adoptee(s) and their family. These include being "different" from the parent(s), developing a positive racial identity, and dealing with racial/ethnic discrimination.[130] It has been found that multicultural and transnational youth tend to identify with their parents origin of culture and ethnicity rather than their residing location, yet it is sometimes hard to balance an identity between the two because school environments tend to lack diversity and acknowledgment regarding such topics.[131] These tensions also tend to create questions for the adoptee, as well as the family, to contemplate. Some common questions include what will happen if the family is more naïve to the ways of socially constructed life? Will tensions arise if this is the case? What if the very people that are supposed to be modeling a sound identity are in fact riddled with insecurities? Ginni Snodgrass answers these questions in the following way. The secrecy in an adoptive family and the denial that the adoptive family is different builds dysfunction into it. "... social workers and insecure adoptive parents have structured a family relationship that is based on dishonesty, evasions and exploitation. To believe that good relationships will develop on such a foundation is psychologically unsound" (Lawrence). Secrecy erects barriers to forming a healthy identity.[132]
The most recent adoption attitudes survey completed by the Evan Donaldson Institute provides further evidence of this stigma. Nearly one-third of the surveyed population believed adoptees are less-well adjusted, more prone to medical issues, and predisposed to drug and alcohol problems. Additionally, 40–45% thought adoptees were more likely to have behavior problems and trouble at school. In contrast, the same study indicated adoptive parents were viewed favorably, with nearly 90% describing them as "lucky, advantaged, and unselfish."[144]
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.[118] 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.[119] 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.[120]