I can't answer that question exactly. I'm not currently in touch with many in my JW family.
When my mother joined, 5 of her siblings joined also. Two of the 6 of them eventually left the JWs when they were like 39 and 45.
My sister and I and 13 of our cousins were raised as JWs. As far as I know, only 4 of the 15 total cousins remained active JWs past age 35. I was the first to leave. Those 4 also had children raised as JWs.That would be 13 people total. I'm uncertain what those children's current status is in the Borg. Although, I'm pretty sure that most of them are still affiliated with JWs. They would all be over the age of 18.
The whole JW thing has affected our family greatly and we are not close because of it. With no get-togethers for Christmas or other holidays you never see these people. There is quite a bit of alcohol abuse, multiple divorces, major depression, a suicide, total estrangement from family, severe mental illness, and people that have never married, gotten good educations or decent jobs among this clan. How much of it I can blame on the negative JW environment is debatable but I believe it is a factor.