Are Most Twins Left-Handed or Right-Handed?

According to SAEDNEWS, An analysis of studies on twins across 19 different investigations shows that most of them are left-handed; approximately 15% of twins are left-handed. These studies have been conducted on populations worldwide, so it is correct that twins have a higher likelihood of being left-handed compared to non-twins. In this section, we will examine some points regarding this topic.

Is the number of left-handed individuals different between identical and fraternal twins?

In 1999, research showed that there is no difference in the number of left-handed individuals between identical and fraternal twins, and in all of these studies individual characteristics of people and twins were taken into account.

They generally examined the number of left-handed individuals in identical and fraternal twins and found a difference between these groups. The number of left-handed individuals in identical twins was higher than in fraternal twins in these studies; however, further and more extensive research showed that there is almost no difference between them.

Are twins always the same in terms of being left-handed or right-handed? For example, if one twin is left-handed, is the other twin necessarily left-handed as well, and vice versa?

As you probably know, identical twins originate from the same fertilized egg, and therefore they are genetically completely identical. If you are left-handed or right-handed, you have inherited this trait entirely from your genes, so identical twins should, in theory, be the same in this regard and show no difference, meaning both would be left-handed or both right-handed. However, this may not apply to fraternal twins, and even identical twins can have exceptions. Approximately 20 to 25 percent of identical twins are considered exceptions.

What about triplets? Do triplets also have a higher likelihood of being left-handed?

Studies conducted worldwide show that the probability of being left-handed among triplets is approximately 11%. These studies also indicate that triplets have a higher chance of being left-handed compared to the general population, but a lower probability compared to twins.

Interestingly, this research points to a factor influencing this tendency in triplets, which is low birth weight.

On average, triplets who each weigh less than 1.5 kilograms at birth are more likely to be left-handed than others.