When you are getting a fair number of them from a wide range of breeders, chances of them all being genetic are slim in my opinion. Not to discount that genetics could have bearing inin SOME of the cases. If all the crossbeaks were coming from one breeder, or from one set of parents, the chances of it being genetic increase, but from unrelated parents?
The year I hatched a number of unrelated chicks with crossbeaks was the first time I used mash chick feed (a very powdery one). I changed back to crumbles, and while I cannot say I never get a crossbeaked chick, it is not more like one per breeding season--and the last two years I have hatched at least double each year more than the previous year. So a difference of something like 1 out of 10 when I used mash and now have about 1 out of 200. To me that seems to be significant. Mind you, the year I had the most crossbeaks they were completely unrelated to each other--different breeds.
I've done a fair amount of research on crossed beak (aka tweaked beak and scissor beak), and based upon what I have read, as well as my own experience, crossbeak that shows at hatching is almost certainly genetic. Crossbeak that shows up 2-3 weeks later can be genetic, but is as likely to be a result of injury as of genetics. Pecking something too hard too often when the chick is young and the beak is still soft, or food impacted between the inner edge of the beak and the outer edge seem to be the most common causes of injury. (Sorry, I do not know the names for these parts of the beak, but if you pry a bird's mouth open, you will see what I mean.)