This article is a training resource for scientific writers, not a guide on what you're allowed to call your grandma, which is entirely your business. However,

This article is a training resource for scientific writers, not a guide on what you're allowed to call your grandma, which is entirely your business. However, like everything else, language is a practice, and it can't hurt to practice your awareness of what might constitute impolite vs formally appropriate speech, even if you consciously choose to ignore it in casual conversation.