Question about Categories set up - how can I show products from subcats in parent?

I wanted to know if it was possable to do this. if you go to my site http://www.gottagreatgift.com and you click on kids it as 2 sub-cats boys and girls but it does not show any products it only has small text at the top of the Sub-cats Boys and Girls. Is there a way that when they click on kids that it will show every product listed in kids and take away the text links at the top. and if the user wants they can click on girls or boys in the menu to the left?

This thread provides some background, and I believe that there may also be a mod that allows this, but don't know whether it affects display only or display and data (that will make more sense after reading the thread referred to earlier).