Family members in Russian. Do you know all of them?
To make you feel better – young people now don’t use/ understand a lot of those words, but the older people do.
I’d say those words are good to be added to your passive vocabulary, not worrying too much about bringing them to the active use.
Exceptions: тесть, тёща, свёкр, свекровь, зять, невестка. These words are commonly used. I’d recommend to learn them for sure.