Overall, handedness doesn’t really matter
Of all the interesting facts about handedness, probably the most important one, says Yeo, is that it doesn’t matter much at all. “The differences between righties and lefties are really rather subtle, and of much greater scientific interest than any kind of practical use,” he says.
Grimshaw agrees, noting that mixed-handers seem to differ from “strong handers,” much more than left- and right-handers differ from each other. “However, we really don’t know much about the brains of mixed-handers, because we’ve been so focused on the left-handers,” she says. “Hopefully we’ll have a better understanding of them soon.”
One thing is for sure, Yeo says: We shouldn’t assume much about people’s personalities or health just because of the hand they write with. And we certainly shouldn’t worry about lefties’ chances of success: After all (as of 2015), five of our last seven U.S. presidents have been either left- or mixed-handed.
Mind & Body – Health.com