Why are some people left-handed and others right-handed?!?!??!

Probability and genes (look below)

Explanation:

It depends on your genes. If both of you parents are right handed, you'll be right handed as well. If one is left handed and the other is right handed, there a 50-50 chance you'll be either. However, if, lets say, your grandparents from your dads side (his parents) are one right and one left handed, and hes right handed, you could be left handed, even if your mom is right handed. If you want to know THAT probability, I'd bore you to death with x and y chromosones (spelling lol) and punnett squares.

i think people used to doing stuff on one hand better and they are addicted to that hand . Like example you already used to right land and you try to throw a tennis ball but your left did not throw the tennis far away then you right hand throw a far away. Well that my opinion

Explanation:

answer; health-related quality of life;