Children grow up in all kinds of homes from all kinds of families. They grow, learn, and develop into all kinds of adults. The color of the parents' skin, whether or not they have a disability, the gender of either or both parents does not matter. What matters is if that person or those people (whether it be a single mother/father/aunt/uncle/grandmother/grandfather/coach or 2 married individuals) can provide a stable, loving environment for the child or children. As long as the parent(s)/guardian(s) can provide the basic needs for raising a child and can always provide lots of love, those children will be set up for success in life because at least they have a chance.
Denying a child a home to two parents who are desparate to have a child based on race, gender, or sexual orientation is not only a slap in the face to the parents, but is cruel to that child who needs a home. By discriminating on those factors, you are assuming based on stereotypes that all same-sex parents are incapable of providing a good home. You are assuming that only 2 white, heterosexual, cis-gender parents are capable of raising a child, and that all other parents are beneath them.
No matter what the family is like, good adults and bad adults come from all different backgrounds. Discriminate against ALL people equally, or don't discriminate at all.