It's an approximate and symbolic number, i heard it started at 4 actually, probably due to multiple traumatic events and abuses. I don't know which one in particular. It went progressively better starting from 16 i think. Then i became a moderate stutterer for something like 7 years. Then a casual stutterer for another couple years. Now i can speak fluidly for hours, but very rarely, have a block coming from nowhere to say something like "au revoir" (bye). Or "bonjour" (hello). I did the Tomatis method for years when i was a teenager. It's not a quick result but maybe it helped. It helped me a lot when i finaly met my first friends, i mean true friends who respected me as i was. My big stepbrother in particular was so patient and respectuous. He helped me a lot to accept myself as i was. I don't know if weed helped. I wish i would have tried EMDR. I think i'll do it when i'll have time. Never too late