The legal definition of parent according to Lawyers.com is one who "begets or brings forth". Unless there is a miraculous conception, only two people with opposite genitalia are capable of "begetting" offspring.
The negative answers to this argument are addressing a different question. They might be considered valid arguments if the question were asking if heterosexuals were the better "caretakers". But that hypothesis is not quantifiable scientifically and the answers would necessarily be based on conjecture.
Heterosexuals are the only kind of parents. Compare the children of one man and one woman (the entire population of Earth) with the children made through gay sexual activities (there are none). Clearly the children of straight sex are more successful, since they exist. Get your false gay religion out of our schools and teach real science - Johnny does not have 2 daddies. That is impossible and it's sick to teach children lies instead of science.
I understand the question as 'would heterosexual parents raise a happier, healthier child?' Rather than 'Are homosexuals physically able to reproduce with one another?' which would be the most logical understanding here.
In response to the argument that heterosexual parents are better parents because they are biological: Does that mean that an infertile woman would be a terrible parent? Or, say, hypothetically that a young girl got pregnant, 15 years old, she has no money, no job, she's still in school, her boyfriend ran a mile when he found out, her parents are not supportive so she has no way of giving that child a good quality of life, so she gives it up for adoption- would the adoptive parents then not be parents?
I agree with a previous comment stating that homosexual parents are more likely to be better parents because they choose to have a child in most cases, whereas 38% of heterosexual pregnancy's in 1999 where unplanned (J. Joseph Speidel, Cynthia C. Harper, and Wayne C. Shields (September 2008).)
You don't have to have any particular parts to be able to screw up your kid - you'll figure it out. Being a good parent involves a lot of things, but I don't think that making sure your partner is the opposite sex is one of those things. Children need: love, nurturing, room to grow, strong support for their individuality, and to be taught how to respect, feel empathy, and love themselves and the people around them. None of those things are things that ONLY heterosexual parents do, and they're definitely not things that ALL heterosexual parents do just because they're heterosexuals.
There is no evidence what so ever that quality parents depend on sexual preference. It seems to me that any make up of people willing to love and teach a child, then they will make good parents. How does sexual preference even come into this debate? How about we look at parenting methods and love instead?
One's sexuality has nothing to do with one's ability to be a good parent. That would be like saying people with blue eyes are better parents than people with brown eyes. There are wonderful gay parents and there are wonderful straight parents. There are also horrible gay and straight parents. It's about the person, not the sexuality of the person.
At least one study has shown that homosexual parents actually tend to be better than heterosexual parents. The findings found that homosexual parents were better prepared for children, for the simple reason that in order to have children, they must deliberately seek out that possibility. So it's not that homosexuals are better parents- it's just that the good homosexual parents tend to be the only homosexuals who actually are parents, unlike heterosexual parents. What this indicates though, is that homosexual parents can be just as good as heterosexual parents. It's not the sexuality, it's the quality of parent that matters.
I was raised by straight parents who wrecked my life. There are plenty of heterosexual couples who should not be parents. So what, because they don't have matching genitalia they're suddenly better parents? I think it takes a lot to become a parent and be a GOOD parent. It doesn't matter who you are or who you love, race and sex should have nothing to do with being a great parent.