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Right-left tilt said to develop early

Whether a person will be right-handed or left-handed could be decided early in the womb when the fetus is about 10 weeks old. Scientists who studied ultrasound scans of 1,000 fetuses and followed the progress of some of them after birth found that if a fetus preferred to suck its right thumb more than its left at 10 to 12 weeks old the child tended to be right-handed. ''The hand you favor as a 10-week-old fetus is the hand you will favor for the rest of your life," New Scientist magazine reported Wednesday. The findings, by Peter Hepper and researchers at Queen's University in Belfast, Northern Ireland, challenge current thinking that hand preference does not develop until a child is 3 or 4 years old.