Back in the dark ages when I was growing up, parents knew the parents of everyone I hung around with. They made it a point to do so without fail. If my parents did know the kids parents, well tough luck for me.
I do not see that with a lot of parents today....even with my own grandkids....lots of people seem to be too naïve or too self absorbed to take the effort. Age difference or not, you must without fail pay attention to what is going on in your kids lives.
Too many parents today are too concerned about being their kids "friend" instead of being the mentor they need.
Just like Doc mentioned, open the windows so you can hear what is transpiring. Don't just stick your head in the sand.
Or your face in the damn phone.