[quote=looneymommy]Note they become sterile when your population limit is reached. If your population limit is say, 30, and your population is 30, no one else can become pregnant until your population limit goes up. When your population limit is reached is the best time to mate them like crazy to create Master Parents as they will never get pregnant and can be mated over and over and over .. sort of like Ft. Lauderdale during spring break.