The Mouse Twins are relatives of Mickey Mouse, presumably his cousins.
The Mouse Twins are identical twins, and probably cousins of Mickey Mouse. This might make their parents Mickey's Aunt Victoria and Uncle Albert. They used to come to the annual Christmas party at Mickey's house wen he was a young child. Mickey keeps a picture of them in his house.
Behind the scenes
The Mouse Twins first appeared in 2016 in the cartoon story Duck the Halls. They are probably based on the Grady Twins from the movie The Shining.