If you've watched any movies or films where there's a parent/child dynamic, the parent always views their child as children, no matter the age. My mom does this to me a lot. When I visit her for dinner, she'll make three dishes-chicken, beef, and a vegetable entree. She makes enough to feed an family of four, but it's just the two of us eating. First she'll say that all of this costs less than a single entree at a restaurant. Then as I take a piece of chicken, she'll point to the beef dish and ask if I don't like beef. I take a piece of beef, and she points to the vegetable dish and ask if I don't like vegetables. I take some and put it in my bowl, and she points to the chicken. She asks me why I won't eat the chicken.
Over the years of mediating between parents and their children, I've noticed that parents are reluctant to change their role. As babies, parents provide everything-food, clothing, healthcare, etc. When children get older, the amount of care needed lessens. Obvious, right? You're not going to prop your ten year old on the table and change their diaper. If you do, then there are issues of discipline you'll need to deal with. During the teenage years, kids tend to want some sort of independence. That's why they don't like to be seen with their moms or dads. It's totally uncool. Once people grow into young adulthood, then further on as adults, parents still care and worry about them as if they were little kids. As children grow, so must the parent's role.
When I taught privately, my advantage was not having any emotional attachment. I would listen to my students problems or issues, and I wouldn't judge them. Some had sex early on. Other's cussed a lot. Many had complaints about their overbearing parents. They told me everything. I'd help them if they wanted, but left the subject if they didn't. Parents would be thankful that I was there to listen to their children's problems, but didn't really know how to gain their child's trust. It's simple, but can be hard to do.
Listen to them, ask questions about what they're talking about, and do your damned best not to judge. Don't overreact, yell, scream, or solve their problems. Ask if they need help, for sure. But just listen. If you want to give your two cents, then ask if you can give your opinion. Trust me, if they want it, they'll say yes. IF they don't want it, and you give it to them, it'll go out one ear and out the other. That doesn't mean you don't make them aware of issues of sex, drugs, or alcohol. You do. I'd recommend not to be overbearing.
I live by two guidelines when I teach. The teacher appears when the student is ready. So if people are ready to learn, they will listen. When I teach, I don't teach, nor do I take the role of teacher. When I teach, I take the role of guide. Life is a massive landscape of unknown. Just as you would hire a guide for a safari, be your children's guide when they need it.