Abaixo segue uma compilação de alguns estudos e revisões recentes publicados em revistas científicas indexadas (naturalmente não pretende ser uma listagem exaustiva - muito longe disso, é apenas uma pequena amostra mais ou menos aleatória das centenas de publicações sobre o tema).
"Twenty–three empirical studies published between 1978 and 2000 on nonclinical children raised by lesbian mothers or gay fathers were reviewed (one Belgian/Dutch, one Danish, three British, and 18 North American). Twenty reported on offspring of lesbian mothers, and three on offspring of gay fathers. The studies encompassed a total of 615 offspring (age range 1.5–44 years) of lesbian mothers or gay fathers and 387 controls, who were assessed by psychological tests, questionnaires or interviews. Seven types of outcomes were found to be typical: emotional functioning, sexual preference, stigmatization, gender role behavior, behavioral adjustment, gender identity, and cognitive functioning. Children raised by lesbian mothers or gay fathers did not systematically differ from other children on any of the outcomes. The studies indicate that children raised by lesbian women do not experience adverse outcomes compared with other children. The same holds for children raised by gay men, but more studies should be done." Anderssen et al. 2002.
"Does parental sexual orientation affect child development, and if so, how? Studies using convenience samples, studies using samples drawn from known populations, and studies based on samples that are representative of larger populations all converge on similar conclusions. More than two decades of research has failed to reveal important differences in the adjustment or development of children or adolescents reared by same-sex couples compared to those reared by other-sex couples. Results of the research suggest that qualities of family relationships are more tightly linked with child outcomes than is parental sexual orientation." Patterson 2006.
"While there has been a recent upsurge in the number of studies related to children raised by gay and lesbian parents, the literature in this area continues to be small and wrought with limitations. This study presents a meta-analysis of the existing research and focuses on the developmental outcomes and quality of parent–child relationships among children raised by gay and lesbian parents. A total of 19 studies were used for the analysis and included both child and parent outcome measures addressing six areas. Analyses revealed statistically significant effect size differences between groups for one of the six outcomes: parent–child relationship. Results confirm previous studies in this current body of literature, suggesting that children raised by same-sex parents fare equally well to children raised by heterosexual parents. The authors discuss findings with respect to the implications for practitioners in schools." Crowl et al. 2008.
"While myths exist that call into question the parenting ability of gay and lesbian parents as well as the impact of such parenting on children in their care, there is an ever increasing body of literature that clearly demonstrates the capabilities of these parents with their birth children. However, there continues to be a dearth of research on gay and lesbian adoptive parents and their children. To address this deficiency in the literature, this article explores the parenting styles of gay and lesbian adoptive parents and strengths of their children between the ages of 5–9 years (N = 94), using scores from the Parent-as-a-Teacher Inventory and the Behavioral and Emotional Rating Scale. Results illustrate that the gay and lesbian adoptive parents in this sample fell into the desirable range of the parenting scale and their children have strength levels equal to or exceeding the scale norms. Finally, various aspects of parenting style significantly predicted the adoptive parents' view of their child's level of care difficulty which subsequently predicted the type and level of strengths assessed within their adopted child. Recommendations for practice, policy and future research are highlighted." Ryan 2008.
"This study compared gender identity, anticipated future heterosexual romantic involvement, and psychosocial adjustment of children in lesbian and heterosexual families; it was furthermore assessed whether associations between these aspects differed between family types. Data were obtained in the Netherlands from children in 63 lesbian families and 68 heterosexual families. All children were between 8 and 12 years old. Children in lesbian families felt less parental pressure to conform to gender stereotypes, were less likely to experience their own gender as superior and were more likely to be uncertain about future heterosexual romantic involvement. No differences were found on psychosocial adjustment. Gender typicality, gender contentedness and anticipated future heterosexual romantic involvement were significant predictors of psychosocial adjustment in both family types." Bos & Sandfort 2010.
"Claims that children need both a mother and father presume that women and men parent differently in ways crucial to development but generally rely on studies that conﬂate gender with other family structure variables. We analyze ﬁndings from studies with designs that mitigate these problems by comparing 2-parent families with same or different sex coparents and single-mother with single-father families. Strengths typically associated with married mother-father families appear to the same extent in families with 2 mothers and potentially in those with 2 fathers. Average differences favor women over men, but parenting skills are not dichotomous or exclusive. The gender of parents correlates in novel ways with parent-child relationships but has minor signiﬁcance for children’s psychological adjustment and social success." Biblarz & Stacey 2010.
O corpo da literatura acumulada a respeito antes levou à Associação Americana de Psiquiatria a declarar em 2002:
"The American Psychiatric Association supports initiatives which allow same-sex couples to adopt and co-parent children and supports all the associated legal rights, benefits, and responsibilities which arise from such initiatives."
E no mesmo ano, a Academia Americana de Pediatria declarou:
"A growing body of scientific literature demonstrates that children who grow up with 1 or 2 gay and/or lesbian parents fare as well in emotional, cognitive, social, and sexual functioning as do children whose parents are heterosexual. Children’s optimal development seems to be influenced more by the nature of the relationships and interactions within the family unit than by the particular structural form it takes." (reafirmando seu posicionamento em 2009)
E, em 2004, a Associação Americana de Psicologia publicou sua resolução:
"Therefore be it resolved that the APA opposes any discrimination based on sexual orientation in matters of adoption, child custody and visitation, foster care, and reproductive health services;
Therefore be it further resolved that the APA shall provide scientific and educational resources that inform public discussion and public policy development regarding discrimination based on sexual orientation in matters of adoption, child custody and visitation, foster care, and reproductive health services and that assist its members, divisions, and affiliated state, provincial, and territorial psychological associations."