One fun thing to do with boy/girl twins is to see the "Nature vs Nurture" theory play out. Over the past 18 months we've seen clear gender differences in Boo and Bear's development. Bear loves all things mechanical: opening doors, fiddling with latches and Boo loves stuffed animals, talking and shoes (seriously!). Boo hugs the baby doll and Bear throws it aside, totally uninterested. I decided to put them in the driver's seat of our 24ft company truck and see their reactions.