>>38211146OP's whacked out because like...
it's easy to put the "it's a fetish" bandaid on it, right? And in theory, he could just say that about it and nothing else and they'd be confused but maybe drop it.
BUT, these are people you spend time around a lot. These are the people whose opinions - if you have a healthy familial situation - might matter most to you. So the goal is to explain it away and rationalize it to make them think you're not a freak, but think about how hard that's gotta be if your family isn't intimately aware of the internet culture surrounding Pokemon. My mother did marketing and management for a swinger's club for years, and she's still like "haha furries are so weird xDDD". To explain it, you'd have to dig yourself into the hole of "it's a rated E video game. you know, for kids! and these look suspiciously like animals!" and then pray to god you can dig back out with "but they're smart! like people!"
tl;dr
OP could just tell them "it's a fetish", but it's still a weird one.
explaining it to them would be... hard, unless they're extremely interwebs-savvy.