with my first two i didn't find out but i had the feeling of first being a girl and second being a boy and i was right, actually we didn't find out the sex until around 10mins after born.

with my 3rd i HAD to find out, i needed to prepare myself emotionally and physically, i am thankful i found out because i got through alot of issues and had counselling before my dd was born, however i do remember saying hmmm now i know i don't really want to know iykwim - oh and my dh didn't want to know (which he regrets now as he has been going through a few issues) so me, my mum, my ds (he was sooo good at keeping secret lol) and bb as well.

i always said if i was lucky enough to do it all again i would definately not find out, but that is just my personal opinion of course

good luck in what you decide