Stereotype, maybe it is but with the First "Lady" appearances render it a true image. She is muscular and masculine.
Many years ago my mother in law had a housekeeper named Jessie.
Michelle is the spitting image of Jessie. M looks like J facially with the high cheekbones and her body is identical. They both are very tall with long muscular arms. Not fat just big! They both come from the same tribe, if you catch my drift.
The secret to tell is that people-groups often stereotype themselves, but no one with a sliver of observational powers is supposed to notice.