That makes sense. But it still seems to me that there are factors that these objective measurements cannot account for.
I'm not arguing with you. It's just that moral development is subjective and therefore nearly impossible to quantify. But the measures discussed above health, grades, etc are indictment enough, if the children raised by gays are found to be lagging behind those raised conventionally, when all the other variables are controlled for (income of parents, type of housing, age of parents, quality of school district, etc).
One of the other posters mentioned that some of the studies show that children raised by homosexuals tend to have a higher rate of homosexual behavior themselves, and that this statistic may indicate that the behavior is learned or influenced, not just hard-wired. "Longitudinal" studies can bring this aspect to light -- studies of a given set of individuals over many years.