My practice Sim just met a Magician. He has 5 traits (only 3 of which I know so far), and the "Try for baby" option did come up. He spent the night with her, and is now her boyfriend. When I finish my practice game, I plan to give her the young again LTR, and see what happens if they get married.
She became his friend by doing the Charming Introduction and then tutoring him in something. When she tried to chat, he ran away, but she was able to call him and invite him over.
If they have children, I'll try to figure out if they have any hidden trait.