Single Gender Species
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Basic Information

A single gender species (also one gender race) is a species (or, in RPG terms, a race) which consists (or appears to consist) of only a single gender.

This is not entirely impossible, even without the intervention of biotechnology or magic - there are numerous species which either reproduce asexually (and thus don't require more than one gender), or can reproduce sexually but are also capable of parthonogensis (and thus could, theoretically, exist without the males of their species almost indefinitely). Any naturally occuring SGS would realistically need to be all female (or at least would be likely to be defined as such by a non-SGS), but might well have situational "gender" roles depending on their social role1. A "male" only SGS requires advanced science or magic. Hermaphrodites are always an option as well - sequential hermaphrodites are likely to be almost indistinguishable from a bi-gendered species until you have known one long enough, but a species of simultanenous hermaphrodites would qualify as an SGS.

The other option is that a species actually does have more than one gender but bizarre sexual dimorphism means that the two (or more) genders are either so unalike that they are assumed to be different species or are so similar as to be indistinguishable (again, both of these phenomena are found in real life).


1. full source reference

Game and Story Use

  • Absolute buggers to roleplay - but good for hilarious values dissonance, especially if you introduce them into a society with strict gender segregation.
  • A particularly nasty example of this is RuneQuest's broo - capable of reproducing with either gender of pretty much any mammalian species by seeding them with a parasitic spawn. This spawn then grows inside its host, adsorbing some characteristics, before bursting out and growing up (or not) to be a broo. Some magic is involved since the entire broo species are known to be deeply contaminated by chaos.
    • Technically there are meant to be female (or at least female appearing) and hermaphrodite broo … but no specific suggestion that these are actually of another functioning gender or that they are necessarily fertile with other broo.
      • Speaking of which, it's not specified as to whether or not broo can impregnate one another generally. This would seem to be a zero sum game if it were possible, but then chaos is sometimes like that.
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