But recently, my mom bought a carton and every one had double yolks. There are several reasons why a double yolk occurs, says Elisa Maloberti, consumer information coordinator for the American Egg Board. Hens just starting their egg laying careers, meaning very young, sometimes produce double yolks because their ovulation cycle is not quite in sync yet, like all young females entering puberty. If it's not a question of young-old, Ms. Maloberti says, it's genetics.
Some family lines are just more prone to the whacky ovulation cycles that cause double yolks.
It could be that the entire flock is just beginning or ending laying careers. It's nothing weird or sinister or anything like that. Just mother nature at work. The Cincinnati Enquirer , a Gannett Co. Inc. newspaper.