genetic defect vs incubation defects

I have a ch bp from last year that I held back. I kept him becuase he had a kink in his back. It wasnt a bad kink and he eats and shed and poops normally but I did not want to sell him incase it was genetic and someone tried to breed him. Well in the last year he has almost grown out of the kink. As far as being a kink, I wouldnt even call it that anymore, the area where it was is now just slightly flatter than the rest of him and unless you are looking for it its hard to see.
Question is if this kink was a genetic defect is it capable of going away? Or are genetic defects there to stay.
Could it be it was just a development in the egg that went bad ? Could that kind of defect go away?
The only other thing I think it could have been was an injury, perhaps during shipping which seems the most logical of the three possibilities for the defect to correct itself (heal)