The Dabneys are next door neighbors to the Duncan family. Like all the other family's that live on their street they have a D as the first letter in their last name. Mrs. Dabney lived with her husband before he moved out and got divorced (It's a Charlie Duncan Thanksgiving). Their son, Rodney, moved out when he grew up.
There was a picture of Rodney, and he was black. So Mr Dabney must have been black, or they could have adopted him.