My grandfather stuttered. He was ill for many years before he died when I was 8. Sadly, I don't remember him all that well, and unfortunately we were not particularly close when I was growing up. I am 99% fluent now (most people can't really tell I have a stutter, although it is most definitely still there). I assume my stutter is genetic because in addition to my late grandfather, my youngest daughter has it too - and again, it's not like she hears me stuttering all the time.