Dolezal has (partly) black kids, and was married to a black man. A white woman with black kids and a black husband can get a lot of hostility from the white general public - the grandmother in the supermarket who whispers, “You’re nothing but a whore,” the tradesman driving by who shouts, “Niggerlover!” and so on.
One way to put a stop to all this is perm your hair, and smack on an extra coat of tanner. Voila, now you’re a “light skinned black woman”. Now, random passers-by don’t hate you on sight. Now you can be fully welcome in places and groups where your loved ones are not grounds for shunning.
I don’t blame Dolezal at all for how she chooses to identify, any more than I would blame Arnold Schwarzenegger for calling himself a white American and marrying into the Kennedy family.
On average, black Americans are 80% African ancestry and 20% European. This is a mean, individuals often have more or less. Out of the 40 million plus black Americans, there are a couple million who have no African ancestry at all. They’re just as black, in terms of genetics, as Dolezal is.