Because if you don't start the geek education young your kids will think you're too weird and nerdy to be around when they're older. :)
I turned 40 today. My family bought me geeky presents like police box and meeple sprinkles, a TARDIS ornament, a shirt that says "MOM" in binary code and a new copy of Princess Bride (to replace the one I lent to a friend and never got back.) I also got lots of time and space to take photos and do some crafting - secret Christmas sewing, but crafting nonetheless. They know me so well!