WASHINGTON—Wash your hands, folks, especially you ladies.

A new study found that women have a greater variety of bacteria on their hands than men do.

And everybody has more types of bacteria than the researchers expected to find.

“One thing that really is astonishing is the variability between individuals, and also between hands on the same individual,” said University of Colorado biochemistry assistant professor Rob Knight, a co-author of the paper.

The researchers aren’t sure why women harbored a greater variety of bacteria than men, but lead scientist Noah Fierer suggested it may have to do with the acidity of the skin.