Woo commerce

I am having trouble adding product variations and attributes inside of Woo Commerce.

Does anyone know how to add nested attributes? what I mean by this is child and parent attributes. The current example on woo commerce is not sufficient for my example as t-shirt sizes are completely different than shoe sizes.
For example I might have Men’s shoes, women’s shoes, and kid’s shoes. Each of these have different sizes of course, so shouldn’t the “size” drop down be dependent on a previous attributes such as Men’s?

This is not the entire list, but how would you setup something like:
Men’s
13
13.5
12
12.5 and so on
Women’s
11
10.5
10
9.5 and so on
Kid’s
12
.
.
.
2.5