Go ahead and check, we’ll wait.
Who knows who decided to keep track of this and why, but here it is, the least convenient way to tell what hand someone probably writes with. Let’s just get this out of the way: you can always just ask people, or observe them writing something. So many paths to take before we reach down someone else’s pants. Although it’s nice to know we got something out of all that time spent looking at our genitals in mirrors.