He obviously wasn't that fussed for them if he let you take them. I could look at my shelves and tell you exactly what was missing, and kindly give it the fuck back or else thank (space) you.
My dad was very fond of military history for whatever reason. He was an incredibly peaceful man, and never invaded anywhere. The books we read aren't all of what we are, otherwise there'd be a hell of a lot more serial killers out there given how popular true crime is. And I've never met an actual vampire or anything, yet there's books galore about them.