I play a same-sex couple in TS4 that is a remake of one I made for TS3. When I remade Avery, I chose to allow him to become pregnant. Sure, I had always thought of him as male, but apparently he is a Trans man, has been all along, and now is finally ready to have a family with his long time partner and husband, Riley.
Try For Baby worked as usual. Ave took a pregnancy test the next day and confirmed he was expecting. Three days of pregnancy, listening to Alternative and eating nothing but carrots from the garden, he gave birth to a boy, Alf (both from the old root for "Elf" because the original Avery was a Fairy, and from Alpha, A, One, First child).
As an infant, I cannot inspect Alf closely. He is essentially an object in-game. My very strong suspicion, however, is that being a boy, he will have defaulted to "can impregnate others" under gender setting. That setting can, however, be adjusted in live play at any mirror with the "Change Sim" option, without needing mods or cheats.
To summarize: I am not certain but from how the system is set by default, I expect that you will have to toggle the option yourself. I'll allow Alfie to determine his procreative role when he's a YA. Right now, he's too little to worry about it.
Happy Simming!
