When will I know if my baby is a righty or lefty?

Many parents wonder how and at what age their child becomes left- or right-handed. When one hand is consistently used more than the other hand, and is more skilled at tasks than the other hand, then that hand is considered to be the dominant hand. This is also referred to as hand preference.

Your child’s preference for the right or left hand may start to appear as early as 6 to 9 months of age. Even so, you won’t be able to determine true right- or left-handedness until your child is 2 or 3 years old, when the child begins to favour the same hand consistently.

While children often swap hands in fine motor tasks, it is good for a child to develop strength and dexterity in one hand. This will help them to develop accuracy and speed with fine motor tasks, particularly handwriting. This does not mean that the other hand gets neglected! In fact, the other hand has an important role to play as the assistant hand, or “helper” hand – for example, holding the paper still while the dominant hand writes; manipulating the paper while the preferred hand cuts with scissors.

Hand dominance is greatly influenced by genetics. If both you and your partner are left-handed, your child has a 45 to 50 per cent chance of being left-handed as well.

There are four main types of handed preference:

Right-handedness: This is most common, occurring in 70–90 per cent of the population. Right-handed people are more dexterous with their right hands when performing tasks.

Left-handedness: About 10 per cent of the world’s population are left-handed. However, most left-handed people develop some mixed-handedness simply by living in a world where most everyday objects are suited for right-handed people, or by growing up with right-handed parents.

Mixed-handedness: Also known as cross-dominance, is being able to do different tasks better with different hands. For example, a mixed-handed person might write better with their left hand, but throw a ball more efficiently with their right.

Ambidexterity: This is exceptionally rare, although it can be learned. A truly ambidextrous person is able to do any task equally well with either hand.

If you’re curious about which side is going to become dominant in your baby, try offering her a tempting toy. If she’s started to develop a dominant hand, she’s more likely to use that one to reach for it.

As you watch your baby’s motor skills develop, remember that it’s not a good idea to attempt to influence her hand preference. Besides genetics, hand preference in part also depends on your child’s nervous system.

Forcing her to use her right hand when she’s really a lefty is unlikely to work in the long run and will only confuse or frustrate her along the way.

Remember that handedness is not a simple preference for one hand because the two hands actually work together in more subtle ways.

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