After doing some research I may have found the answer to my own question. It seems that as a doe enters estrus she will push her yearlings away until she is bred. Once successfully bred the doe will allow the yearling does to rejoin her but the yearling bucks are not, they are ran off to find there own territory which apparently is natures way of preventing inbreeding. You guys probably already knew this and dont care, but if you wondered there you go take it for what its worth.