What is causing chickens to have crooked bodies?

[Flowerbh]

I visited a friend today who has several chickens that have crooked bodies. The tail and back part of the chicken angles off to the left. I pulled this photo from the internet, but it shows what his chickens look like. Any idea of what it is? Heredity? Mal-nutrition? Disease? Thanks

 

[Egghead_Jr]

Hereditary, it's called wry tail. I think the pullet in that photo is posturing to accentuate the effect but yeah, the tail veers from a straight line.

 

[Egghead_Jr]

I should add that it's not a health defect in anyway. Like split wing it's a combination of many genes that causes it to occur and is really only a visual fault. Some lines have a propensity to these kinds of defects and those birds expressing it are not used in breeding or many of the offspring will express the fault. If only birds not showing these faults are bred then it will appear infrequently. Point being is it's not recessive genes (two recessive express) rather a combination of many genes causing the effect.

 

[Flowerbh]

I should add that it's not a health defect in anyway. Like split wing it's a combination of many genes that causes it to occur and is really only a visual fault. Some lines have a propensity to these kinds of defects and those birds expressing it are not used in breeding or many of the offspring will express the fault. If only birds not showing these faults are bred then it will appear infrequently. Point being is it's not recessive genes (two recessive express) rather a combination of many genes causing the effect.

Thanks. I will tell him. He hatched these birds from a friend who gave him eggs. I will tell him to only hatch my eggs from now on! LOL!