Men think they are 100% straight shooters. Even if we want to believe that the majority of men have perfect aim (which is NOT true), it's clear that most haven't made the quantum leap necessary to understand the difference between a latrine—which is, by definition, a toilet used only by men—and a bathroom that's in one's home, to be used by everyone who lives in the house, as well as by any visitor. Read: Sharing a Bathroom? Cohabitation Tips
Whether men agree with the following statement or not, nothing can change the reality of it: Leaving the toilet seat up is a clear statement of control and power. Somehow, men have designated themselves as "owner of the toilet seat," and have made its "normal" position open—and up. And the problem doesn't stop with men, as this behavior shows children (from the time they are toilet-trained) that when a woman wants to use his toilet seat, she must first put the seat down, every single time she needs to use it.
Here's a scenario that has played out in millions of homes: It's 2:00 AM... she's pregnant... and groggily awakens to go to the bathroom, and doesn't turn the light on. Upon sitting, she's not groggy anymore! She just sat on a cold, wet (with his urine!) porcelain toilet base, and may have also wet her bottom with the water that's in the toilet. (Did he also forget to flush it?) Read: Conquer His-And-Hers Bathroom Clutter