Amazon has a great bit of Gender going on if you're trying to find boots
You might think you pick Men's or Women's and a size, but no!
The sizes themselves are gendered, you have to pick size Mens-10 or size Womens-12, which is separate from the gender option

@foone I have a question.. are shoe sizes non gendered elsewhere?

Australia, UK and seemingly US (at least from the conversion chart I had working selling shoes sometimes in a department store)

all i remember is genders and wondering why.

@LottieVixen No, this is a common thing in the shoe industry, from what I've sen. Amazon's filtering implementation just makes it very obvious