I am going with this:
She wears a wig-—all the time. She has such a wide array of ‘hair styles’—one right after the other that would NOT be consistent with real hair. Bangs-—whatever.
I saw a clip once of the family disembarking from Marine 1 in the White House lawn at dusk, and she had a ‘nappy head of hair’. Nothing longer than a 1/2 inch. Was quite awhile ago, but perhaps someone has it archived.