What is the historical origin and significance behind the direction of fabric folds in clothing?

by wby

So here's a multi-part question I'd love to get some more information on, from both the Eastern and Western perspective.

In general Western clothing, men's clothing goes left over right, and women's clothing right over left. When and why did this become a thing?
In traditional Eastern clothing, robe-like clothing is worn left over right regardless of gender. I have read sources that say that this is to accommodate things being stored in the robe that could be easily accessed with the right hand. Is this correct? As I understand it, in Japanese culture, wearing the robe in the other manner signifies funeral wear. My parents (Chinese-Taiwanese) have told me that the direction of the robe is irrelevant in Chinese culture, and I've had some Vietnamese friends tell me the same as well. Is there any reason that the Japanese have a different view of the direction of fabric folds, or was this a common mentality in East Asia that has slowly faded everywhere but Japan, etc. etc. etc.?

Many sources have claimed this was so men could reach their swords under their coats, & so women's clothes could be buttoned by their maids most easily. This ignores that swords were not worn under coats, but hung so the grip was outside any jacket or coat, from the 1650s when coats replaced the doublet, and the 1780s when men quit wearing swords in the street. It can be noted that many women had to dress themselves, and prefered dresses that laced down the back to those that buttoned.

There was an essay on this over at Costumer's Manifesto. The author studied a huge number of portraits and other pictorial reference and found that men's & women's clothes usually wrapped left over right down the ages. When it didn't, it was a personal preference w/o gender.

Rather, she found that women only began to wear clothing left over right in the late 1800s, with the rise of the tailor-made. Her theory was that in UK and USA there were laws forbidding cross-dressing, and that changing the direction of buttoning let them "prove" that their masculine-style shirt was a female garment because it buttoned "the wrong direction." This then extended until most people believed it had "always" been so.