Criticism criticism criticism !! Ugh

Nakita • Baby 1- June 2015, Baby 2- October 2016, Baby 3- March 2018!
My boyfriend and I has decided we want to find out what the gender of our baby is! We're pretty young (23) but we want to be as ready as we can be. Also it's much easier for a shower! But his family has been giving me a really hard time over this. They think it should be a surprise because that's how they did it and they don't ever let me forget it when the topic comes up! It's getting really hard to deal with I just want to scream. Do they not get this is OUR baby? Anyone else having this problem? What have you been doin about it ?