Studies have been pretty clear on the subject.

A Cambridge University developmental psychologist testified at a federal trial in San Francisco today that broad research has documented that children of same-sex parents are just as likely as those of heterosexual parents to be well-adjusted.

"Studies have found children do not require both a male and female parent," testified Michael Lamb, who heads Cambridge's Department of Social and Developmental Psychology.
The biggest challenge to same-sex parenting is a bigotted environment.