Hate to bring it up, but at the time it was only possible to be positive about the race of the mother. The race of the biological father could be only asserted, not proven.
If she wants to, she can have genetic analysis done and find out for sure. Quite a large percentage of white people who do the test find out they have some African ancestry.
Thank you for not flaming me about being a jerk! You are right... they could really only prove who the Mom was. I truly think they had a child.. determined race may be in question and found her a home. At that time, I am sure it was unheard of for a white family to adopt a black child or the other way around. Sounds to me like they did the best they could for a child needing a home.