There is no sign of injury to the skull or the base of the antler, so it had to be genetic.
Actually this is not true. According to a number of biologists including noted author Leonard Lee La Rue abnormal antler formations are most commonly the result of two kinds of injury. (assuming a head injury is not the cause as you have stated)
First, if the antler strikes any other objects while it is growing it is very likely the antler will bend into an unusual shape and harden in that manner. It is unlikely it would actually fall off as one would expect. This would leave absolutely no visible marks on the deers body at all, and the deer would in most cases grow a normal set of antlers the next season.
Secondly, many deer grow deformed antlers as a result of injuries to a part of their body other than thier head. In most cases this is the result of an injury to the animals hind quarters. The injury can affect the antlers in two ways. First is that the deer bends the antlers when they are still soft,(as is the case in the first example). This often occurs while it is constantly licking its injuries in an attempt to clean it. In these cases the deer will likely grow normal antlers the following year. The second more common explanation on how the injury affects antler growth is that the left side of the brain controls the right side of the body and vice versa. This results in an antler deformation on the skull on the opposite side of the body as the original injury. In this case the deformation will likely last throughout the deers life.
The important point of this is that none of these deformations are the result of genetics and none of the abnormalities would be passed on the deers offspring regardless of whether the deer continued to have abnormal antlers throughout its life. In all of the cases there would be absolutely no signs of any injury to the deers head.
In this particular case the one antler that is not unusual is actually relatively normal in design, this would indicate it was likely a case where it was simply bent while it was growing and hardened in that position.
Must have four points on one side.
