Re: Fertile Trait not working

Made one guy. Made him fertile. Worked on his traits and careers. 

Created 14 women, 14 houses. Made all women fertile. Worked on their traits and careers.

Started off by living with two women at a time, impregnating both (separated by two trimesters so not to fill up the house too quickly), then waited. No triplets.  Moved babies and ladies out, moved two new women in. Repeat. No triplets. Repeat... repeat... repeat.

Once all households were filled with babies (7 babies and a woman), I played each of those households until the babies were taken away. Returned to main character and tried again.Then again. Fail.

Tried different strategy. Moved man into women's houses. Impregnated and waited. No triplets, then moved to the next house and tried again.

Started a new game with one couple. Played them both through careers and traits. Made them monogamous. Made them fertile. Still playing this save. Have now given away 26 babies and no triplets. Twins four times, the rest singles.

Tried making sure they overeat during pregnancy. Tried watching kids tv and putting a bed in the kids room. Tried filling a bedroom with flirty stuff and making sure both sims were "very flirty." Tried getting sims maxed on all traits before having a baby. Tried with zero traits (except charisma from chatting up). Tried potions beforehand. Tried rockets, beds, and hot tubs. Nothing works.

I have now had more than 300 babies across two saves and no twins. Probably way more. Twins about every 4th or fifth pregnancy.  My wife is playing her own save. Built a massive world. Uses full cheats, so no trophies. Even she has never had triplets.

HELP!