Okay, pardon me while I preach to some parents. This has built over the course of my child raising years, so it may sound a bit harsh, but I need to get it off of my chest.
Since when did it become okay to set the bar for our kids' moral behavior to be no higher than our own bad decisions at their age? I cannot tell you how many times over the years that I have heard parents say something like, "well I can't very well tell my kids they shouldn't do that when I did my share of it". Really? Your standard for your kids can't be any higher than your own bad decisions when you were their age?
We don't do this with anything else. I've never heard a parent say, I was not good at sports when I was a kid, so I can't encourage my kid to try out. I didn't get a scholarship when I went to college so why should I expect my kids to apply. It only seems to be an issue when it comes to moral decision making. I've heard statements like this concerning underage drinking, drug use, sex, and just basic disruptive behavior. Parents actually believe they can't instruct their kids not to do things that are illegal, dangerous, and immoral because they themselves were guilty of those things at some point, too.
Just because we survived some of our bad decisions, or we "turned out okay", doesn't mean those were good decisions, and more importantly, it should NEVER be where we look when determining and communicating expected behavior from our kids. I've heard some say it would be hypocritical to tell your kids they shouldn't, when you did. But that is only true if you still think the illegal, dangerous, immoral behavior was a good decision. If that is the case, then you have other issues. But if you believe it to be a bad decision, it is certainly not hypocritical to instruct your kids to avoid that type of behavior and similar decisions. Your kids may make the same bad decisions, but as a parent you should not let it happen because they didn't know better.
One other, sort of mathematical, note on this. If everyone believed and practiced this, then society would find itself in a spiral toward becoming a totally immoral society, with the next generations' moral standards lower than those of the previous generation. Some may say that is where we are now, but I do know quite a few parents who aren't afraid to set the standard for their kids behavior to be higher than what they themselves were able to achieve, and for that I am grateful.