After reading another thread.
I'm fairly young at 30, and when I was wee there was no mention of flossing at all, and I was always taken to the dentist regularly. Same as a teenager. I only started flossing in my twenties when it suddenly seemed to be part of a normal dental hygiene regime, along with electric toothbrushes. I remember reading about flossing in Judy Blume book and it seemed like such a weird idea 
I still remember the sense of injustice at age twelve when I went to my dentist who accused me of not brushing - my mother and I were so indignant - as he didn't realise that diabetes means your saliva is sweeter than normal (and at times in my life when my blood sugar was running high, it must have virtually been like syrup) so causes damage. My teeth were great until my late teens though - I think partly from brushing 3 times a day all through my school days, but my teeth did start to deteriorate then, and I now have quite a few fillings and one molar gone. I don't know if flossing would have helped.
Did you floss as a child - were the dentists I saw back then just very old fashioned? Do you floss now?
Do your kids get started on flossing at a young age with dentists now?