Hey thanks! I’m suggesting that the neighbors were a gay couple in the Ira Levin novel, and re-cast in the film. I think that Levin’s later hit play Deathtrap, where the characters who appeared to be antagonists end up being a gay couple, is a re-casting of the same plot.

On quick search I’m not finding a full “queer reading” of Rosemary’s Baby, charting all its strange gender references, but note that Laura-Louise the witch neighbor is played by the famously lesbian Patsy Kelly.