I believe it runs in my family. I stutter and also my cousin on my dad's side. However, we are quite mild and most grew out of it. I have two kids and only passed it down to my daughter, who also grew out of it and doesn't stutter anymore. I am much much older now and stutter doesn't affect me and I am mostly fluent and can pass myself as a non-stutterer without speech therapy or any other intervention. I just talk a lot at work and volunteering and being the head of the household. Fluency just was achieved by doing more talking.