There isn't an exact answer to this question because most doctors and researchers don't know.
However, I came across an interesting theory on a "Miracle of Life" documentary on the Discovery channel.
Basically, it explored the idea that people who are left handed actually started out their gestational life (in the womb) as a twin. When the egg divided, one embryo got the left handed gene while the other got the right handed. If you were not born with a twin, then your twin was reabsorbed into the womb and wouldn't have shown up in any ultrasounds.
This should not suggest that every left handed person started out as a twin, but there has been some research done on this theory.
churchill was righthanded
I think she is left handed.
Yes, she is righthanded.
Yes, she is righthanded.
yes, but he play drums like a righthanded, like me.
Jennette is righthanded
He threw righthanded and batted righthanded.
Taylor Swift is right-handed.
By the way he plays guitar, he is right handed.
righthanded
No, he was a righthanded batter.
Because for example right handers slide with their left foot up to the foul line. So this shoe is made to slide and the other is made to grip