It seems to me that the music you grow up with as a child defines the music you later listen to. This can work in two ways, a) it can be forced upon you so much that you'll later come to hate it and anything that is remotely like it, or b) you can be taught to love it and continue to love it and things like it in the future.
For me, it was definitely the b-version. I am very grateful to my parents for helping me appreciate the gems and that way help me define my musical standard.
Most profoundly, I remember growing up with the Beatles. I think I was about six when I knew the entire For Sale album by heart. This CD would be played in my dad's car at least once a week, and always, every time, on holiday. At the time I didn't understand what the Beatles meant in their time, what they meant for my parents, or what they would mean to me in time. But I could just endlessly enjoy the songs on that album, and occasional others on the records at home.
Another one of the greats I remember, though in my mom's car, is Bob Dylan. His brilliant lyrics and music would very often keep me distracted in the car, whilst I mused about made-up backing vocals and sang loudly to the song with words that sounded very correct to me, but of course, most of the time, were gibberish. Try Subterannian Homesick Blues in the car with a child. Bound to make you laugh.
Also among the regulars in my dad's car was John Hiatt, though I never quite knew if he belongs to the greats or not. Then again, any artist that makes father and daughter sing together should be called one of the greats. Seven Little Indians was always my favorite.
I always thought I would rebel eventually and betray my family's good taste in music, but I find that the Beatles are still among my most played tracks, and that I like to compare my favorite bands to the Beatles or Bob Dylan, most of the time without noticing. Why, because their music is so timeless.
Mothers, educate your children with the Beatles and Bob Dylan, they deserve it!