Damsel, if you play the piano long enough, you learn to use your hands independently. I'm definitely right-handed, but I type MUCH faster with my LEFT hand. Most of that has to do with piano training....learning to stretch fingers and have "muscle-memory" of where a note, or a letter, is in relation to the whole. SO my personal theory is that "handedness" has as much to do with training as it does with inheritance. People who have strokes or lose a limb, can and DO learn to write with the opposing hand if necessary.
My father & my husband are/were both "lefties" who were forced to use their right hands by the school system. This made both of them able to do almost everything with EITHER hand. Interesting thread, for sure.
I had never thought about the difficulty of x-words for lefties, but I agree that the issue should be addressed. One of you "south-paws" should start a petition for it. I promise to sign