It’s a mixture of your genes which you get from your parents, and also your life experience.
Early infant behavior development of hand preference
Handedness – News, Research and Analysis – The Conversation – page 1
Why Are Some Of Us Left Handed?, Left Handedness
Left-handed discrimination history. Is it a sin?
How likely is it for right handed parents to have left handed
When Will I Know if My Child is Left or Right-Handed?
How children's brains develop to make them right or left handed
Can You Become Left-Handed If You're Right-Handed? Learning To
Helping LH Children infographic
How children become left or right-handed - NZ Herald
left-handedness – News, Research and Analysis – The Conversation – page 1
Leftie parents: What to do for your left-handed children
How to Stop Thumb Sucking: Tips to Break Your Child's Habit