The Powerline blog notes:
A Canadian study by professor Douglas Allen of Simon Frazier University finds that children raised by married biological parents do better in school than children raised by same-sex couples. The study appears in the Review of Economics of the Household, which I understand is a peer-reviewed journal.
The study uses a random 20 percent sample of 2006 Canadian census data. According to the author, this sample size “allows for control of parental marital status, distinguishes between gay and lesbian families, and is large enough to evaluate differences in gender between parents and children.”
The study finds that children living with gay and lesbian families in 2006 were about 65 percent as likely to graduate compared to children living in opposite sex marriage families. Daughters of same-sex parents do considerably worse than sons.