You know what I think is natural.
A male and a Female. 2 men together cannot make a baby. The same for 2 women. Its not possible for them to have kids themselves without science , modification or third party .
So what does it being "natural" benefit? My two front teeth are prosthetic. I know a few guys with prosthetic limbs too. These people wouldn't be able to walk without science, modification, or a third party. What about people who are infertile? They can't have children on their own either. You know what's really not natural? Leaving your kids in a foster home.
I would like to pose a couple situations to you. Of these two situations; which do you think is more likely to be the better option, and why?
Situation #1: Little Sally is placed in the foster system at birth and never adopted. Due to this, she receives very little guidance and lives with the constant frustration of not having a stable household. She spends her entire childhood feeling like nobody wants her.
Situation #2: Little Sally is placed in foster care at the same age as #1. However, a gay couple adopts her and provides her with a stable, loving, and affectionate upbringing; coupled with a good moral grounding. She spends her childhood being loved and wanted by a couple that cares about her.