Ultrasound may disrupt fetal brain development, suggests a recent study comparing Swedes exposed to prenatal ultrasound with those who had not been. ’32 per cent more than expected were left-handed. In an average population, around nine per cent of men are left-handed.

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The results suggest that some men who genetically would have been expected to be born right-handed had actually grown up to be left-handed. (The researcher) says this could be due to a disruption of their brain development in the womb: “It’s commonly known among neuropsychiatrists that right-handed people can become left-handed by slight damage to the brain.” New Scientist