There are many stories of parents bringing their son in for evaluation, and when his ADD is diagnosed and ADD or ADHD is explained to them, the father is amazed to realize that he has it too.
I estimate a 50% chance that my grandfather had it, 2 % chance my father did, 100 % for me and for Duane, my youngest son. ADD or ADHD tends to run in families, especially along the male line. There is less information about in females, but I have seen some suggestion of the same. So it seems clear that there is a genetic component, probably a strong one.
About doug with ADHD
I am a psychiatric physician.
I learned I have ADHD at age 64, and then wrote two ADHD books for adults, focusing on strategies for making your life better. I just published my first novel, Alma Means Soul.
Your Life Can Be Better; strategies for adults with ADD/ADHD
available at amazon.com, or smashwords.com (for e books)
Living Daily With Adult ADD or ADHD: 365 Tips O the Day ( e-book).
This is one tip at a time, one page at a time, at your own pace. It's meant to last a year.
As a child, I was a bully. Then there was a transformation.
Now I am committed to helping people instead abusing them.
The Bully was published in January, 2016.
It's in print or e book, on Amazon.