balancing act

There's this weird thing I often do with my left hand when it's not in use. I sort of hold it in this tense awkward position. I do it when I'm brushing my teeth, when I'm eating and sometimes when I'm drying my hair. Ed calls it my "balancing," explaining that if I didn't do it, I might tip over. I'm not quite sure why I do this or when it started, but after seeing this, I've decided it must be genetic: