Chicken poppy
Fashionably late
Wow! Thats interesting. I had no idea. Thanks so much! Good to know because as of now i have 4 Japanese bantams, and 4 more about to hatch. Somewhere down the road i might consider selling and i wouldn’t want anything bad like deformities to happen.Breeding siblings is generally negative.
I did it for a pair that I had, not realizing that the person I got the eggs from had also bred siblings together. There were no others to breed to or so I thought. I got a real mixup of genes. Good genes, bad genes, mediocre genes and everything inbetween. I got some offspring that were substantially bigger than either parent, substantially smaller than either parent, a few that didn't even resemble the breed and everything in between.
The rooster ended up inheriting a lethal gene from his parents that were siblings. He passed it on to several of his daughters and sons. The gene being that the majority of the chicks that he sired from being bred to his daughters ended up dying in the shell. For instance, one year I did a test breeding in breeding him back to a daughter. Out of thirty two fertile eggs, only four hatched, two of the chicks died before they were three days old, one lived to be four-ish months old and another one lived to be fourteen months old. I opened up the fourteen month old to see if there was something internal wrong with him. His liver and gizzard were twice as big as they should have been.
Generally if you need to breed close it's better to breed son to mother or daughter to father. If you do decide to breed siblings, only do it one generation.
Note: Not all chicken breeds have the lethal gene that I just described above, so don't get scared that just because you breed siblings that this is what is going to happen to you. I just shared my experience for your benefit.