I didn’t know Jarrett was “black,” either. I thought she was Iranian, and while it turns out that she was brought up in Iran, apparently her father was an American of European descent and her mother was part African American. You’d never know it by looking at her, however, so even while I don’t like Roseanne, I don’t think she meant to make a “racist” comment.
She was referring, I think, to Jarrett’s weird Planet of the Apes hairstyle.
I thought I read her dad was the first African-American to get a scholarship to some school.