BELFAST, July 22, 2004 ( – New research from Irish scientists has revealed that a person’s dominant hand is determined by 10 weeks gestation. Scientitsts previously thought the dominant hand was not determined until at least three years old.

The researchers noted that, by using ultrasound, the determination of a preferred hand was set at just 10 weeks, and correlates to the dominant hand later in life.  As reported by New Scientist magazine, of 60 babies who sucked their right thumbs in the womb, 100 percent were right handed when investigated at age 10 to 12, whereas of 15 who sucked their left thumbs in the womb, 10 remained left-handed, while five switched to right-handedness. Furthermore, the 60 to 15 proportion mirrors the proportions of right to left-handed people in the adult population.  Read BBC coverage:   Read the related report:  4-D Ultrasound Shows Babies Smile and Cry in Womb Amazing New Ultrasound Shows First-Ever Pictures of Unborn at 12 Weeks ‘Walking’ in the womb   tv