Good point.
Interesting too because I always thought Junior was biracial in real-life, but both of his parents are black...well black-ish at least. I will say that their family is more realistic than some shows since Rainbow is mixed in real life and on the show. Andre is sort-of middle of the road, not particularly dark or light...just like his parents. The kids came out in a range of colors like you'd expect from a medium black man and a mixed black woman (even though Tracy Ross is not that light for someone with a white parent) but only one is bi-racial in real life (Yara Shahidi).
The mum looks white. If she's not.. she's close.
Having the mixed mum is also political.
Mixed race people are over-represented in AA roles and in entertainment in general. Not actual mixed race characters though... just the people. That's because of colourism.