We found out because I wanted everything to be gender specific. So pink stuff for a girl n blue for a boy. I'm not really into neutral colours or green, yellow n purple on babies. Lol. And I am OCD with organising things so I had to know so I could plan and organise her nursery...
And last reason was that I wanted a girl, dh wanted a boy... We found out at 20 weeks ao there was no chance of even a split second of disappointment at birth...