So the only reason that you have to compare Bristol with Ron Reagan, is that Bristol had premarital sex with her high school sweetheart.
You must have missed the part where Bristol conceived and bore a child as a result of that 'premarital sex'. They were engaged but never married. It was in all the papers. Like Bristol Palin, Ron Reagan also drifted toward 'show business'. He was, in his youth, a ballet dancer, later a (liberal) radio host but he was always an embarrassment to his father. Brother Michael recently accused Ron of just that, after Ron hinted that he saw 'possible' evidence of Alzheimer's disease in his father while he was still president.
Like some of the folks who've deigned to respond to your quixotic defense of Bristol Palin's foolish decision to move in with two men to have their lives used as the basis for a 'reality' TV show, I think it's a poor decision and that the media will attempt to use it to further criticize and ridicule Sarah Palin. Obviously, you believe it's no big deal. So be it. It's hardly worth the amount of time this very minor issue has been given.