I was never one for ramming my musical tastes down my kids' throats. All the stuff he liked he'd discovered for himself; same for my daughter. In the car as a family we always listened to what they wanted to hear. (Or what my wife wanted to hear!). I never played them anything saying "Hey, listen to this!", not even my own stuff. (And I've produced some totally amazing music in my time)How had your son not heard an album you loved and even had a copy in the car?
They were both vaguely aware of what I liked, but they wouldn't have been able to give you specifics.