For most of human history, being left-handed was treated as a flaw, a bad omen, or worse. The Latin word for left, "sinister," said it all. Today that stigma is long gone, but a quieter mystery ...

Left-handedness and sex hormones: Could there be a link to cancer risk? Overall, 10.6 percent of people are left-handed, but we know that men are slightly more likely to be left-handed than women ...