Have you seen pictures of Meghan Markle as a child? She has identifiably light brown skin, and hair that is curly, approaching frizzy. Why would you believe that she didn't consider herself black? Why would you presume that her very identifiably black, social-worker mother did not teach her about who she was?
So, Megan has fair skin and straightened hair. Meghan is bi-racial. Her genes "straddle the fence." Why is it up to us to tell her what she has to "be?"Any time we demand this of anyone, we are proclaiming that they are reduced only to pigment.
I'm pretty sure that Meghan's complexion has helped her in some ways and hindered her in others, because others have also reduced her being to pigmentation. However, she knew she was black, and she knows that she's black. She knew that before marriage. She simply didn't know that she would be treated as "black" in such a public and hostile way.
I don't know what you look like, but I promise you that you are more than your pigment.