First off there should be a 100 question test before one is allowed to even ponder reproduction. If you miss one question, you can't have kids.
After that I could care less who has children. Any form of a family is better for a child than growing up in a group home, orphanage, foster care, on the streets. Whatever.
As for the "who can you fuck and it still be legal" evasion, you can fuck whatever you want but some shit ain't gonna be with the societal flavor.
Just a interesting side note. In some Southern states, it is still considered to be sodomy when sex is engaged in, in any method other than vaginal and missionary. Falatio and cuninlingus are both off the menu.