The conundrum of toilet seat placement has been professionally investigated.
When mathematicians (I'm one) decided to tackle the problem of toilet seat placement, I got interested. The results of applying game theory to the question of "Leave up or down?" are interesting.
Assumptions had to be made, of course: The female performs more toilet operations because of a smaller bladder, but the male drinks more beer. Not considered was potential prostate problems.
Mathematical calculations demand the seat be left in its last-used position. Researchers, however, conclude that the seat should be placed down after toilet use. It turns out female hectoring is more compelling than science.