Did she really get a letter saying “no girls allowed”?
There’s no evidence of it, other than her repetition of the story (which doesn’t hold much weight with me, considering the source). As Jim Oberg points out, she certainly could have been part of the first class in 1978 that admitted women, had she applied herself. But her degrees were in political science and law, which certainly weren’t indicative of someone who desired a career in spaceflight. I wouldn’t be shocked to learn that she couldn’t handle technical subjects, or math.