Our findings challenge received notions about the importance of children having both one female and one male parent. In this sample, regardless of whether they had one mother and one father, two mothers, or two fathers, children were thriving. Our findings are also at odds with the notion that only heterosexual adults make capable parents and that lesbian and gay parents are somehow ineffective or harmful. Inasmuch as there were no significant associations between parental sexual orientation and child adjustment, our results are consistent with notions that two parents of the same gender can be capable parents and that parental sexual orientation is not related to parenting skill or child adjustment. […] From a policy perspective, our results provide no justification for denying lesbian and gay adults from adopting children. Indeed, barring adoptions to prospective lesbian and gay parents seems likely to produce a number of undesirable outcomes.[…] In jurisdictions that bar same-sex couples or lesbian and gay individuals from adopting, fewer children were adopted from foster care. Thus, it appears that more children could potentially benefit from having permanent homes with capable parents if lesbian and gay adults were allowed to adopt in the U.S. and elsewhere.
— Researchers Rachel H. Farr and Charlotte H. Patterson, of the University of Virginia, and Stephen L. Forssell of George Washington University, writing in Applied Developmental Science and arguing their research doesn’t simply conclude gays make great parents, but that any policy prohibiting it is utter nonsense [via; PDF]