Often those types of problems are nutritional, like the hen laying the egg was either lacking in certain things or not digesting properly. It can happen to anyone, but if GFF was feeding something that was lacking in something, it can do it. Not necessarily genetic.
The only surefire way to know would be to breed the lame birds and see if they throw more like themselves. They'd want to hatch out a good 20 eggs. If none of the offspring get it, then it's diet.
The problem is there are a few different causes for that, and you'll never know what caused it in that case. It can be genetic, from breeding poorly where you're inbreeding (not a bad thing if done *right*) and end up doubling up on crooked genetics. It can be from breeder nutrition. It can be from incubating and hatching poorly (crooked toes most notably). And it could even be from improper chick nutrition, if it's showing up a little later rather than straight out of the shell.
I've been about 80% accurate with wing sexing on day olds, you can try that.....gold feather farms is where I got the eggs . They look like good stock just bad luck if all are boys. Have two one day olds now maybe I'll be lucky on at least one of them.
Maybe it depends on what line/strain you got... I dunno. But I'd say about 1 out of every 4 that I wing sexed as pullets always turned out to be boys.
