I had a surprise this morning… a double yolk egg. The two yolks seemed to have about the same volume as the single yolk eggs. This made me wonder, do fertile double yolk eggs hatch two live chicks? It seems like the yolks wouldn’t be sufficient to feed each chick and the hard shell would restrict growth.
IANACR, but wikipedia has this to say:
Thank you. I don’t know why I didn’t just google it.
Even with human intervention, it’s pretty hard to get a double yolk egg to be viable.
Then there’s whether the egg was fertilized, anyway. Likely not.
When our 5th grade class (10-11 years old) did our embryology unit, I got a double yolked fertile egg. My teacher wanted me to discard it and choose another, but I begged and begged to keep it, and acknowledged that I understood they would likely die and promised not to turn into a basket case over it. They both grew and I could see both hearts beating and see two little outlines when we candled them. They grew to fill the egg, and then one day one of the hearts wasn’t beating anymore. It grew a dark spot that spread, and after a few days the other heart stopped beating. That was a few days before everyone else’s eggs hatched.
My teacher wouldn’t let me crack open the egg to do a necropsy.
A woman after my own heart. I would have wanted to know what happened too.
Judging from my wife’s record, nearly all human intervention with any* chicken eggs isn’t viable.
*Except scrambled, sunny-side up or over-easy.