As long as children have loving, stable, and responsible caregivers - it doesn't matter who they are.
Well, it's not entirely fair to say that it doesn't matter at all. Although those qualities are paramount, who the actual caregivers are does in fact influence the situation to some degree.
It's not sexist to say that a girl would feel more comforted talking about purely female biological issues from another female who has personally experienced those very same issues herself. It is also not sexist to report observations that males and females generally hold different roles in societies throughout the world.
It is my opinion that children gain more social-emotional balance from both male and female caregivers. It is valuable for developing children to absorb both male and female energy.
Energy includes: physical appearance, tone of voice, fashion, and general tendencies.
Non-Issues include:
Kids raised by same sex parents are not at all more likely to become gay themselves. Sexual orientation is a
biological preset - Yes I said it!
Boys with two moms are not always going to be "sissies."
Girls with two dads are not always going to be "butch."
"We're gay and we will raise our kid better than most people!"
Great! The world needs more good parents! But please consider the following:
2 dads - Find a female who can be some part of the child's life. This can be a friend, relative, or "Big Sister."
2 Moms - Find a male who can be some part of the child's life. This can be a friend, relative, or "Big Brother."
Summary
Having loving, stable, and responsible caregivers is absolutely the most important thing - Period.
Yet kids are still best off when they have this foundation provided by both female and male caregivers. That doesn't mean that kids are guaranteed to have problems if they don't, it just means that they are even more benefited when they do.