(CNN) — Of all the arguments swirling around the legality of same-sex marriage, it’s clear that a major concern is, as always, the kids.

Supporters argue that same-sex parents need to provide their children with a stable and supportive family home, complete with the legal protections afforded heterosexual married couples. Opponents claim that children raised by same-sex parents are wounded in some fundamental way by being denied the “normal” benefits of having both a mother and father at home.

What is lost, remarkably, in both these arguments is the science that enabled families headed by same-sex couples to exist at all.

Until recently, families had to consist, at least at the outset, of a mommy and a daddy, each biologically necessary to bring children into being. Even if the mother died in childbirth or the father disappeared shortly thereafter, the physiological basis of the nuclear family remained intact: one mother, one father, and a child conceived of their union.

Click here to read the entire article.