Some families are just nosier than others...lol My family would probably be the opposite, raising an eyebrow if I were hauling a casual date home or on a double with my brother and his wife. Just keep expressing to your family that you're happy with your relationship status or lack thereof right now - most parents just want to know their kids are happy. Leave it at that.
You and I see this a little differently - not talking about what turns me on and my intimate proclivities doesn't really strike me as lying. There are simply things that aren't anyone else's business. Even without sharing the nitty gritty details, talking about a basic overview of a BDSM lifestyle is still pretty intimate and nudging toward the sexual. Not things I benefit from by chatting about with the fam. Your mileage may vary.