Just an FYI Nrass Woohooer mod has an option to allow same sex pregnancies but you would still need to download pregnancy morphs- the mod has links to compatible morphs provided. The base game DOES in fact 'allow' same sex pregnancies but it's more of a glitch than regular game play. Most of my neighborhoods are 'gay'- I went through and did romantic interactions with most of the males which turned them gay when I had just the base game installed. I was a little upset that same sex pregnancy was not allowed but at that time I didn't know about Nrass.
Then all of a sudden multiple men in the neighborhood started to have the floaty head syndrome- where only their head and feet appeared. I was convinced that my game was corrupted but when I looked online about it...there wasn't anything but a few mentions of teen pregnancy having this problem. So I switched families and what did I find- babies! Babies listed with mother and father BOTH male. I think there were 6 or 7 families that had children like that...but I could never get their bodies back. That's about the time I found Nrass and I've been happily creating babies ever since.
Nrass also gives you the option of 'choosing' who takes the mother role by designating who becomes pregnant (initiator/ target/ initiator then target)