Something I was told was staying in the same bloodline (father to daughter, granddaughter, etc) would actually produce larger and more uniform racks...I tried it for the past couple years and really didn't notice any difference, however.
In other animals, not necessarily deer...but I'm sure it's just as likely in deer, with inbreeding, you increase the chances of bringing out any genetic problems especially recessive problems since if they both carry a recessive gene for a particular unwanted trait, it'll bring that trait out...or something along those lines. Genetics hasn't always been one of my stronger points...