I too have bi-racial grandchildren and others in my family that are from different cultures.May I suggest the first thing is teach him to love himself. Tell about his greatness. No one should be judged by the color of their skin. You stated that maybe he wants to white like us. He can't so give that up as a possibility. Get him a mentor of color. male of female. So he can be rich in heritage. My grand daughters are 11 and 10, my son is raising them alone he being of darker skil and the childrens mother is white. We teach them that they are beautifully different and unique. If you would like to discuss this more please PM me.
Altheia