Mother in law

I know that I am sensitive because I am pregnant but my MIL will only entertain the idea of my baby being a boy. I honestly don't have a preference but I have a hard time biting my tongue. If anyone says they think it's a girl she'll say no "only boys in our family we never have girls" when we were visiting yesterday I had told my husband on the way over it has started to annoy me and he didn't really think anything of it. Well she showed us some clothes she has bought for the baby and it was only boy clothes. I feel like she isn't allowing me to enjoy the surprise. I know she doesn't mean any harm but I'm going to go crazy biting my tongue. Anyone else's MIL do this?