I'm not :D Exposure to higher rates of testosterone before birth can lead to a left-handed child.This is the Geschwind theory, named after the neurologist who proposed it, Norman Geschwind. It suggests that variations in levels of testosterone during pregnancy shape the development of the fetal brain. Testosterone suppresses the growth of the left cerebral hemisphere and so more neurons migrate to the right hemisphere. The highly developed right hemisphere is now better suited to function as the center of language and handedness. The fetus is more likely to become left-handed, since the right hemisphere controls the left half of the body. The theory goes on to tie the exposure to higher levels of testosterone and the resultant right-hemisphere dominance to auto-immune disorders, learning disorders, dyslexia, and stuttering, as well as increased spatial ability.
I'm a lefty, (well, actually, I write with left and do everything else with my right).. my boyfriend's the exact same way. My dad's ambidextrous, my mom was a lefty, brother, grandma, a few of my friends, ... I know a lot .. us lefties need to stick together. :P
Theory I always heard was that the gene that makes you left handed is recessive, and not as common. So both parents would have have the gene to give it a chance to show up. Geschwind is interesting too tho. And makes about as much since so idk
nicee... my babysiter was lefthanded :D and few of my relatives :))) an I must admit that it is kind of a privilegy to be one. If you are interested, you can read the book Right Hand, LEft Hand, by Chris McManus :))