Antler development is very complicated. Genetics plays a role but, most importantly it is nutrition on a bull that is healthy with no injuries or genetic predisposition. A bull that receives an injury to certain areas, say the left rear leg, on one side at the right time will often have a abnormality on the opposite side. Why one bull grows larger antlers then another from the same area is the riddle. Being nutrition is so important in development. Take me pages to explain my thoughts on it. One thing to look at is the spread at the pedicle. Each time it sheds it looses a little more on the outside then the inside thus increasing the spread.