as a shed hunter Ive looked in the same areas yr after yr and found a few drop tine sheds 1 place in particular Ive found a couple that look exactly alike and I chalked it up to genetics I ended up killing 1 of those bucks it has a 9 inch drop tine

I say genetics. I've only seen one drop tine buck in PA. I found his shed but he had broken off the drop tine already. This buck had a forked G2, a 3 inch sticker coming out the side of his mainbeam and the drop tine, that was a good 9 inches. He was living in a park that's closed to hunting.

Its both. Genetics cause drop tines but injuries also cause irregular antlers which sometimes leads to drop tines. Usually the irregular antler will be on the opposite side of the body as the injury.