This is an affect well known in some domesticated animals like sheep, it's well known that if sheep are, if, if, if, if ewes are well fed just before they mate, they're much more likely to er to twin than if they're er not given extra food supplement and nowadays erm  farmers wh wh who, who breed sheep for lambing er frequently feed, feed ewes a special diet just before er conception for that very reason, the rate of twinning increases.