I have two points, Mary, about something you said here regarding any person who grew up in an opposite-sex, two-parent home. First, probably not everyone would agree, particularly if the home was not a loving but an abusive one. Second and more importantly, of course almost everyone who GREW UP this way would not want it to be different. A same-sex parent arrangement is foreign to them and may seem strange. Further, if they grew up in a loving home, why would anyone want the family structure to be different?
Concerning the research, preliminary evidence suggests that a loving home is more important than whether the parents are opposite- or same-sex. The older research still stands, however, for the most part, in that if a home is deprived of a second parent, by means of divorce for example but also the death of one parent, that has repercussions on the child’s future development. It is also the case that two genders do help the child in their development, so same-sex parents are NOT the ideal, but neither are they detrimental. In reality, one might ask, are there any parents who raise their children in an “ideal” way? Parents make all sorts of mistakes but their children, for the most part, turn out fine.
If one is morally opposed to this type of child-rearing, that is another issue. Insofar as Catholic agencies’ favoring only opposite-sex adoption, that is their moral and religious right. They should not be forced by the State to do otherwise.