Most babies use both hands and rarely show any preference before about 7 to 9 months old. By about 18 months many children use one hand more than the other, but up to age 4 to 6 years, children may still use both hands rather than favoring the right or left.
Catching and throwing a ball is not always a good way to tell hand preference. Some ways to tell if your child is left-handed include:
Whether a child is left-handed or right-handed depends mainly on how the baby’s brain develops before birth. It may be caused by genes passed from parent to child.
About 1 in 10 people are left-handed. Males are about twice as likely to be left-handed as females.
There is no great disadvantage to being left-handed. Many famous and successful people throughout history were left-handed. Your child may need tools and supplies made for lefties, such as baseball mitts, hockey sticks, scissors, and spiral notebooks.
Left-handedness is related to the brain, not the hand. It is not just a habit. Forcing a left-handed child to switch to the right hand may cause problems with language or trouble learning to read and write.
If you have concerns, have your child checked by your healthcare provider.
If you are right-handed, sit across from your child when teaching them to tie their shoes or get dressed. This gives them a mirror image to copy, and is easier than sitting beside them to show them what to do.
When your child reaches school age, make sure that he or she doesn't have to sit at desks for right-handers. When students start to write, they should learn paper and pencil positions for the left-hander. For example, it helps for the left-hander to hold her or his pencil a little higher than the right-hander.
For more information, see http://www.lefthandedchildren.org/