I'm a lefty too - the only one in my family - including grandparents, aunts/uncles, and cousins. And, no, I'm not adopted. I write, bat, shoot, etc. left only. The only thing my right hand is good for is helping hold on to stuff and typing. And I love that the eTrex Legend is so perfectly designed for the left hand.
I'm not evil, but I think there are some others out there that would say differently - especially when it comes to some of the cache hides my caching partner and I have placed.