Oh, but it does! Google "D4DR" and you will see. Read the article I wrote in the OP, above, click on some of the links I provided at the end of it.
When I was told that there was a genetic connection to thrill seeking I thought the psychologist who told me was joking. She wasn't.
For what it's worth, DZ.com used to be owned by a company called "D4DR Media". Or something like that.
You are right, when I was thinking genetics, for whatever reason I only thought about inheriting genes from my parents. They are completely different then I am. As a matter of fact, I am the only person in my current family tree that probably has the D4DR gene.