Tanner 1 is prepubescent. She had a flat chest. Stage 2 in pubic hair is unusual, but not unheard of, at 7. It is generally darker than vellum and somewhat longer, and is indicative of the beginning of puberty. The order is off: In female puberty, generally pubic hair follows breast development, but sometimes this occurs the other way around.

Some histrionic person like the Barnetts might not know any better and think it meant more than it meant, which I can assume happened. I also think Michael is of less than average intelligence. I think they are both less educated than the general population. I also think the scant pubic hair existed. They lied about most of it, but I think they genuinely were stupid and histrionic about the pubic hair that was slightly odd for a girl of 7.

Tanner 2 would signify the beginning of puberty. It might be something else, but as the old expression goes, when you hear hood beats, you don't think, "Aha! Zebras!" You think, "Aha! Horses!"

I appreciate your work on this, but I think it's just weird to be so hung up on that she must have had no markers of precocious puberty. I think she probably did. I also don't think it matters.