re: #37 sagehen
Who says extraterrestrials have the same number and type of genders as earthlings? I vividly remember a sci-fi story (Asimov maybe?) where the alien race had 3 genders and reproduction could only take place within a triad.
I can’t remember who, but I vaguely recall a sf story where a space crew is warned not to have sex with the natives, one of them does, and discovers he will be the father to several thousand offspring.