Martians and humans were both self-aware life forms but they had gone in vastly different directions.  All human behavior, all human motivations, all man's hopes and fears, were heavily colored and largely controlled by mankind's tragic and oddly beautiful pattern of reproduction.  The same was true of Mars, but in mirror corollary.  Mars had the efficient bipolar pattern so common in that galaxy, but the Martians had it in a form so different from the Terran form that it would have been termed "sex" only by a biologist, and it emphatically would not have been "sex" to a human psychiatrist.  Martian nymphs were female, all the adults were male.