I think that needs to be elaborate a little bit.
And btw, I just had a name to call them ^^ (Grey Owl, Dolezal, Elizabeth Warden,etc..)
they're 'trans-ethnic' people.
The term transethnic should be separated/distinguished in 2 categories..
1.
Analogous Trans-ethnic or People who alter their physical ethnic group within their own range. I.e= Blond to dark or dark to blonds. Nordic caucasian are certainly different than southern european ethnicities and even more different than aryan middle east through persian although some northern european like Irish is eventually has natural dark locks/features but the rest of west/northern european might need a bit make over. Nevertheless..the result isn't too staggering from light hair to dark hair..and even more if you change your hair color from brunette to blond or to red..
like wow..so dramatic
So, remember..whenever you color your hair..if you try to emulate other caucasian ethnic feature different than yours- you might accidentally practicing element "trans-ethicity"

BUT..to be a true trans-ethnic, you should have feeling not belong to your own kind, if it's not otherwise, you're safely normal ^^.