May I ask, what are the ethnicities/nationalities/religions involved?

I had a friend who was African American, he married a Japanese woman who was here working as nurse. Her parents disowned her (lots of racism against blacks in Japan at that time) but they came around a couple of years later when their beautiful grandchildren were born.

Is ethnicity the ONLY problem? Or does her mom object to her being with a guy who is older, or who doesn't want kids, or something like that?