It’s a mixture of your genes which you get from your parents, and also your life experience.
Are You Left or Right Brained?
Why are some people left handed? Curious Questions with Answers
Is it right for my child to be left-handed?
Curious Kids – News, Research and Analysis – The Conversation – page 1
When Will I Know if My Child is Left or Right-Handed?
How to Tell if Your Baby Is Left-Handed: Plus 3 Tips to Help Them
Handedness – News, Research and Analysis – The Conversation – page 1
Early infant behavior development of hand preference
Why are some people left-handed and others are right-handed? - ABC
Left-handed discrimination history. Is it a sin?