It seems to me that people worry about the past way too much. What people have done wrong, the mistakes that they made, and the times they screwed up. Why do we care so much how somebody was in the past when we have a chance to learn about them in the future. People learn from their mistakes to make their future better. Some, however, do not and are made from what they are in the past when they have the opportunity to change.
I personally try to get to know someone by who they are now because you aren't what you were a couple years ago. If I constantly worry about how someone was in the past then I might be missing out on the great person they may have become. Most of the time I don't even want to know their past because it can ruin the future.
Learn from your mistakes and make for a better future.