Does "on ley line" work for you?!

I got my alien sims the fertile reward (one for mom and one for dad), got the mother a fertility massage and popped them in an on ley line lot trait house. They had one baby (that's Astridon btw, the little toddler in my avatar.) I tried again, and got her the massage again and she still had one child. I ended up cheating loads of babies bc I'm impatient. But when I did the same thing with my other family I *think* I got twins the first time.