SO being weird about skin color

I hate the terms light skinned and dark skinned. We're all black. But I'm lighter and my SO is dark. I made a comment to him about our son coming out chocolate and he got extra defensive saying he isn't dark skinned so it's not possible. First off, he is "dark skinned" so idk what he's even talking about. Secondly, I'm not that light so the chances of our son being dark is very high. I could care less what my sons complexion is as long as he's healthy. I just think it's weird that he doesn't consider himself dark skinned and I'm wondering if he'll feel some type of way about our son if he comes out dark skinned. My SO has 3 other kids and their all very light because their half Puerto Rican. Now I'm concerned about my son being treated differently if he takes his dads skin tone vs mine.