2 Nieces...What can they ethnically call themselves?

They are mixed children. There is beauty in this. Appreciate them for who they are and forget about what label to place on them. Are they fun, Do they like to draw, them being mixed is only a problem to the ones who are not willing to expand their horizons and change the ignorant mentality. I am not saying you are ignorant by the way. Love and enjoy all of them.