Why are women's buttons on the opposite side from men's?
Nobody's certain, but the usual answer given is that men's clothing buttons the left side over the right because that's easier for right-handed people to manage, while women's clothing does the reverse because, in Victorian times, ladies didn't button their own clothes, but had maids to do it. As for the maids, their clothes weren't fancy enough to have buttons.
An alternative answer is that women nursed on the left side, near their hearts, and reversing the button opening made this easier for them.
We confess we're more than a little skeptical about these answers, and we're not alone: Cecil Adams presents both, and is no more satisfied with them than we are. But they're the best we have to offer.
If you like this sort of thing, check out our Timeline of Modern Fashion.