If you've ever found yourself ironing a pile of button-down shirts you may have noticed that the weird fact that on many shirts, women's buttons are on the left side, while men's are on the right. The reasons for the button differences go back a long, long way.

One theory is that men's shirts buttoned on the right because of weaponry. Since most men held their swords in their right hands, they needed to be able to swiftly open their shirt for dueling purposes. "It was more convenient and quicker to use their left hand for unbuttoning," according to a Quora thread via The Atlantic.

 As for why women's shirts button on the left, it's because of babies. Women tend to hold their infants in their left arms, so that their right hand can flip through Facebook (or whatever our foremothers did while breastfeeding). As one theory goes, to make breastfeeding easier, shirts were designed to be opened or closed with the free right hand, so were buttoned on the left, and open on the right.

If breastfeeding wasn't the cause, horses might be. Back in the day, women were expected to ride horses sidesaddle, with both legs on the right side of the horse. Buttoning up on the left may have reduced the breeze flying up their shirts as they had a ladylike trot through the fields.

According to The Atlantic, there's another theory involving Napoleon. As you may have seen in history books, Napoleon had a habit of sticking his hand between the buttons of his shirt. Apparently women would troll him by striking his famous pose themselves. When he heard about the teasing, Napoleon may have ordered that women's shirts be buttoned on the opposite side of men's to put an end to the fun.

Elle notes that another possibility for the difference in button placement dates back to the rise of emancipation when women started to toss off their girdles in favor of trousers and other styles borrowed from men. Manufacturers put buttons on the left side of women's clothing as a practical means of distinguishing between men's and women's clothing.

Melanie M. Moore, founder of women's blouse brand Elizabeth & Clarke, has a different theory on button placement. "When buttons were invented in the 13th century they were, like most new technology, very expensive," she told Today last year. "Wealthy women back then did not dress themselves — their lady's maid did. Since most people were right-handed, this made it easier for someone standing across from you to button your dress."

In short, there are a lot of reasons why men's and women's shirts might be buttoned differently, but at this point in history, there's no reason other than good old-fashioned tradition.