I agree with Farm Hunter. Thin the herd a little, maybe get some supplemental nutrition and see what happens. If it is the genetics, maybe he got that gene from his momma, the doe. He could have a recessive gene for perfect 6X6 racks that he could pass along if he mates with a doe who also has that gene. You never know. I would hesitate to wipe out all inferior bucks. Thin the does out first.