On shirts, they’re on the left for the ladies and on the right for the gents. That’s because of horses, babies, and Napoleon.
1. Because of Napoleon.
The greater part of his representations have his right hand tucked into the coat which must be accomplished if the fastening was from left to right. It is said that ladies used to stick their hand in simply as he did, imitating and taunting him. He then requested all ladies’ attire to have buttons on the inverse side with the goal that they could no more do that.
2. Because upper-class women didn’t dress themselves.
While men usually dressed themselves when it came to dressing, women in yesteryears had servants to do that for them. Since servants were mostly right-handed, it was easier for them to have the buttons on the left.
3. Because of breastfeeding.
It was easy for men to unbutton their upper-wear with their left hand as their right was preoccupied with a sword, especially during warfare. As for women, they held babies in their left hand to keep their right hand free for unbuttoning their top to allow babies to breast feed.
4. Because of horseback riding.
Women, to the extent women rode horses, rode sidesaddle, to the right—so putting their shirt and dress buttons on the left reduced, to some extent, the breeze that would flow into their shirts as they were trotting along.
5. Because of gender inequality.
Another theory says that to prove that women are equal to men, many features of men’s clothing were borrowed by them. But they did want to put in a few changes to indicate that they are different too. Hence, buttons on opposite sides.
6. Because of Manufacturers & producers
One theory holds that manufacturers took advantage of little differences in clothing to emphasize bigger differences between the genders. The left-right button differential wasn’t, in that sense, so much a matter of practicality as it was one of philosophy. (For a corollary to that, we can thank, again, Napoleon.