Rachel Dolezal did a service. Racial identity is a social construct. Black and White are identity, not genetics.
There are many instances of families slipping into Whiteness over the generations. Why not the other direction?
What Dolezal did shocks us because we can’t believe she would prefer Black over White.
She deceived with regard to her genes as a byproduct of choosing her identity. There were few explicit lies, and they weren’t about important things. The deception, not the lies, is what disturbs people.