I am left handed, and I remember I studied this topic in a college genetics class - the professor was very fascinated by the concept of 'handedness', because his wife and 3 kids are left handed, but he is right handed. There is without question a genetic component to handedness, but it is unclear how it is passed, and indeed, some aspects of handedness are acquired via life experience, making it further complex.
As part of the class we took a quiz to discover what type of 'handedness' we had. You could be strongly left handed, strongly right handed, and anything in between. Example, although I am left handed for the obvious tasks of writing and eating, I use my right hand to throw, right foot to kick, right hand to cut, right hand to brush my teeth and carry my purse on my right side. Turns out I am only weakly left handed. For you right handers, you can think about all these tasks and may notice you actually veer left for some of these!
And what the heck are left handed chopsticks?! That's like having a left-handed spoon/fork/pen. That made me laugh.
Finally, in terms of writing, being left handed did affect me growing up. This is because when I was younger, we would write out our essays with pencil, and as you write you rest the left side your hand on the page. As you continue to write, you slide the hand forward left to right (if you are writing in a language that is oriented from left to right, like English), causing the edge of your hand to smear and smudge your writing, as well as get on your hand. Many left handers I knew therefore would curl their wrist up to avoid touching their writing, resulting in messier writing or just looking very odd as they wrote. I myself hated the 'left-hand hand curl' and learned to tilt my paper at an angle when writing. As I got older this tilt got more and more severe, and now I essential write top to bottom rather than left to right. Not a bad thing, just a little unique.
But wait! you say, that means writing left handed is fine for writing Chinese top to bottom. But alas, it is not, because Chinese writing is based on brush strokes - and if you look at fine Chinese calligraphy you will see that the fat parts of stokes are where a typical right handed person would apply pressure as they swept the brush across the page. So sadly, I will never be a Chinese calligraphist. It also means that when I write in China, people are shocked and amazed. I do not exaggerate - once I was cornered by some shop ladies in China and forced to demonstrate how I would form Chinese characters while they laughed and clumsily used their left hands to imitate.
By the way, the left-hand right brain concept is somewhat of a myth or rather misunderstanding based on split-brain research pioneered by neuroscientist Dr. Michael S. Gazzaniga in the 60s.
(
http://www.nytimes.com/2011/11/01/s...phony-of-competing-voices.html?pagewanted=all)
Above is an excellent article on his life/experiments that helps you understand how the split brain works - although that is just for fun; it is not relevant as far as anyone has proven on handedness.
