Double or multi yolk eggs whilst very enjoyable are actually a fault. They are common in young, laying hens, especially from hens that are from highly productive strains.
A double yolk egg is formed when two ovulations take place almost at the same time and go down the oviduct together and both get encased in shell.
Double yolks in eggs (also know as double yolkers) are in fact quite rare but if you like the yolk, more than the white in eggs then it's a rather nice surprise when you open it to find you have two or more yolks!
Poultry genetics says there should only be one yolk per egg. There would be insufficient space for two chicks to develop inside a shell and the breed would effectively die out.
As the hen matures, she will normally only lay single yolk eggs. Double yolk eggs are in fact a fault that occurs when two or more yolks are released inside the ovary at the same time, causing them to be wrapped in albumen (white) and then an outer shell.
It isn't possible to find breeds of hen that will consistently lay double yolkers unfortunately although some shops will sell double yolk eggs where these have been selected when they are candled for blood spots and other problems at the packing station since a premium price can be charged for these.
It is rare but people also find more than 2 yolks in a multiple yolk egg. The most yolks ever found in an egg was 9!
Have you ever found more than 3 yolks in an egg? If so, please send us a photo so we can show it here!