Personally, I can't quite wrap my head around this reasoning. Gays and Lesbians have been raising children for a long time. Since Mr. Morton seems to think that some kind of parliamentary committee needs to study the matter, perhaps we should point them to existing literature on the subject of homosexual parenting.
Or, perhaps more succinct is this piece of testimony , which is pretty blunt.
Switching over to the APA (American Psychology Association), we find this, which is a reasonably decent summary of some twenty years of research.
Guess what? Children raised in a home headed by a same gender couple turn out just fine. In fact, the APA paper has a very nicely worded conclusion:
In summary, there is no evidence to suggest that lesbians and gay men are unfit to be parents or that psychosocial development among children of gay men or lesbians is compromised in any respect relative to that among offspring of heterosexual parents. Not a single study has found children of gay or lesbian parents to be disadvantaged in any significant respect relative to children of heterosexual parents.
So...just what is this "harm" that Morton and others are yapping about? (Besides their fevered imaginings of how GLBT people live)