Question: y do boys have boy bits and girls have girl bits??x

Pete Etchells answered on 25 Apr 2012:

It’s to do with genes – girls have two sex chromosomes which are the same (two X chromosomes), and boys have two different chromosomes (one X and one Y). Chromosomes contain DNA, which contains all the information that makes us ‘us’. Having a Y chromosome means that you produce lots of a hormone called testosterone, which cause male genitalia to develop. If you don’t have a Y chromosome, then you produce lots and lots of a hormone called estrogen, which causes female bits to develop instead 🙂