Rubyfruit Jungle and Zami

Zami and Rubyfruit Jungle: The two books have several striking similarities, so many that my head started mixing up the stories because I was reading both simultaneously. One, they are both sort of set in the Village (they are both set at least partly in New York, and much of the maturing of the lead characters happens there). Two, they are both about women who were somehow on the margins of the mainstream in terms of identity, aside from the fact that they were gay (Audre was “Black”, while Molly was adopted and a “bastard”). Third, the protagonists of both books were very intelligent girls at school, but then their lives got messed up. Fourth, they both had early almost-sexual experiences with female friends. Fifth, both had sexual relations with men, multiple times. Sixth, both talk about unsafe abortions. Seventh, both talk, in an almost Freudian sense, about mothers in rather sexual tones (Zami, explicitly so).

Anyone else notice any more similarities? Also, why are there so many similarities to their stories? Does it have to simply do with being lesbian during a certain period, and that I might find these same similarities if I were to read other lesbian-related books from corresponding periods, or is there more to it? There are differences, certainly, but the similarities are so striking, and almost perplexing (because what these two protagonists have in common is so different from my own experience or those of other girls close to me -- though that might have to with differences of culture/time period).