Everybody, go ahead and cross your arms right now. Done? Alright. Now, try to cross them the other way. If you’re currently crossed with right forearm on top, try to switch position so that your left forearm is on top. Feels incredibly awkward and unnatural, doesn’t it?
It turns out most people have a natural bias for arm-crossing direction, with slightly more than half of most global populations preferring the left-forearm-on-top approach, although the two preferences are basically 50-50. Some people apparently cross their arms either way without even thinking about it, although this population is exceedingly small.
So why do we humans find one way so natural and the other way so incredibly weird-feeling? It may have something to do with your psychological composition, according to the (admittedly somewhat unreliable) Japanese Internet.