In the 1970s, as adoption search and support organizations developed, there were challenges to the language in common use at the time. As books like Adoption Triangle by Sorosky, Pannor and Baran were published, and support groups formed like CUB (Concerned United Birthparents), a major shift from "natural parent" to "birthparent" occurred. Along with the change in times and social attitudes came additional examination of the language used in adoption.
Previous research on adoption has led to assumptions that indicate that there is a heightened risk in terms of psychological development and social relationships for adoptees. Yet, such assumptions have been clarified as flawed due to methodological failures. But more recent studies have been supportive in indicating more accurate information and results about the similarities, differences and overall lifestyles of adoptees.
"Honest Adoption Language" refers to a set of terms that proponents say reflect the point of view that: (1) family relationships (social, emotional, psychological or physical) that existed prior to the legal adoption often continue past this point or endure in some form despite long periods of separation, and that (2) mothers who have "voluntarily surrendered" children to adoption (as opposed to involuntary terminations through court-authorized child-welfare proceedings) seldom view it as a choice that was freely made, but instead describe scenarios of powerlessness, lack of resources, and overall lack of choice. It also reflects the point of view that the term "birth mother" is derogatory in implying that the woman has ceased being a mother after the physical act of giving birth. Proponents of HAL liken this to the mother being treated as a "breeder" or "incubator". Terms included in HAL include terms that were used before PAL, including "natural mother," "first mother," and "surrendered for adoption."
Adoption practices have changed significantly over the course of the 20th century, with each new movement labeled, in some way, as reform. 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, create confusion regarding genealogy, and provide little in the way of medical history.
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."
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.
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.