My parents try to act enthusiastic about the things I like, even if they don't like the thing themselves. My dad has watched some Ghibli movies with me (he actually liked Kiki's Delivery Service), and I've shown him a few episodes of Little Witch Academia. I don't think I've shown any anime to my mom.
So long answer short, they only care about anime because it's something that I care about, and I'm thankful for that!