Mind your own beeswax – today it means “mind your own business” or “it’s none of your business. There are many ideas circulating about the source of the idiom. The most prevalent is:
This idiom came from the days when smallpox was a regular disfigurement. Fine ladies would fill in the pocks with beeswax. However when the weather was very warm the wax might melt. But it was not the thing to do for one lady to tell another that her makeup needed attention. Hence the sharp rebuke to “mind your own beeswax!”
The phrase actually seems to have come into popular usage in the 1930’s, and is just a facetious way of saying “Mind your own business” with a little bit of humor to take the sting out.
The first record of “mind your own beeswax” actually appears in 1929 in a children’s book, with additional early records following in 1934 and 1939, quite a few years after women were supposedly slathering wax on their faces and coining popular expressions about it.