I hadn't been keen enough to catch it in young hatchlings and did not see it until outdoor sunlight was shining on them. So maybe it got a little worse with time, poor lighting in my house, just inexperience and not used to looking for it. NONE in my first generation came that way from the original breeder. Once discovered I culled immediately. I did not get a chance to do test mating and find out who was throwing it before moving on from that variety, but sold WITH disclosure/powerful information if used... 3 out of 30.. is 10% cross beaks.I've read about EE's coming from some Hatchery and there were quite a few folks that purchased from the same place and many of them had chicks with crossbeaks. One of the threads was full of information and it was stated that it was likely the parent stock passing it on rather than any other factors.

Mentioning both factors is a good policy! though I agree it is most likely genetic.. it's POSSIBLE there are times it isn't.. and it's not (always) my place to smash people's HOPE.
The seen deformities I DID get from known temp flux during power outage and known good genetics resulted in very bent toes/ folded under foot for 50% of that hatch. Other times when something like splay leg showed up would be a single chick in the same incubation parameters and same flooring as ALL other that hatched with zero issue.. and is considered by ME to be genetic anomaly/weakness which I also cull for immediately NOW. This is being put out for informational purposes and consideration only according to MY personal experience, investigation, and CURRENT understanding/perspective, etc.
I have also seen a nutrient deficit caused wry neck.. in OLD hatching eggs and shipped chicks.. which I do NOT consider genetic weakness PER say..
Each situation definitely requires individual scrutinizing assessment and consideration to make heads or tails of any possible reality.
Hatchability Problem
Page 52 is where hatch failure analysis starts..
Incubation guide
Sorry if I provided those links before.