Rachel can be who she wants to be and that's up to her. I don't think her actions are truly hurting anyone and the saddest part of this is more how her upbringing informed her decision to identify as black.
I think the 'outrage' felt by some is maybe a little overblown and the personal struggles of one person cannot be compared to an entire race - nor should they - but the persecution and hatred she's received is a bit much.
Shame, as she's probably destined to live out the rest of her life in relative uncomfort as a result of the world's inability to accept difference, whatever form it comes in. It's not illegal what she's doing so it's a shame it's become so controversial.