That's rather strange concerning your parents, for me it's completely opposite, but then again, my stutter is really mild and I don't stutter like most people do. But, I stutter a lot less around people such as my Mother, grandfather, grandma and stuff like that, I feel more comfortable around them and less likely to be judged. Caffeine and a lot of the other things do not affect me what so ever, but everyones case is very different, I consider myself rather lucky, but still people do not understand the toll that having a stutter can take on your every day to day activities, it's rather.. annoying.