Thanks everyone.
I've always just culled anything that was "off". Wry tails or necks, incorrect leg color, wrong combs, or any other major fault. I never really thought about whether it was genetic, just didn't see the point in using anything substandard for breeding.
The reason I posted this was I had a breeder come by the farm this week, we were looking at a few of my breeding projects and I have one hen that is gorgeous, but has a slightly wry tail. I pointed it out as one of the ones I still needed to pull out of the breeder grow out pen (where I grow out all the birds I plan on using for next years breeding projects) and butcher it before I set up next years breeders.
He pitched a fit, said he would love to have it for his breeding stock. I was just sorta shocked, then got to wondering if it was genetic or invironmental. Like I said, I was just curious, I've been raising chickens for many years, but learn something new every day!