Family keep pressing boyfriend about his trauma

I've been with my boyfriend for two months and I found out he's a columbine survivor. He actually told me that on our second date. I told my parents but I didn't think they would press as much as they did. They're fascinated by him and every time they see my boyfriend they want to talk about it. Asked if he knew the shooters. Was he close to them. How was he feeling in the moment. How did he hide. He just seems extremely uncomfortable. And asking once is one thing. They are constantly just wanting to talk about that. I know my boyfriend is uncomfortable because he doesn't really want to talk about that trauma whenever he sees my parents.