Is it hypocritical when parents who have done illegal drugs in their lives (I'd bet half the population has tried something illegal) tell their kids "Don't do drugs?"?

Tonight I went to visit some good friends of mine who have a teenage son. They recently found out the son has been smoking weed. The neighbors (kid’s friend) found out their son had been, and so my friends drug-tested their son and he was positive for marijuana. They took his car away for a month and are now not too happy over his choice of friends and his drug use (he admitted to smoking it for the past 3 years).

However, my friends and probably most of my friends have all, at the very least, tried marijuana and many have been heavy pot smokers, in addition to some of us having done cocaine, etc. in the past.

Of course, my friends want what’s best for their son, and they are afraid that he will go down the wrong path in life. So, is it hypocritical for parents to tell their kids “don’t do drugs” when they have done so themselves?