On two separate instances, first with Tora Ziyal and again in the episode "Covenant," Dukat impregnates a Bajoran woman, seemingly without any medical intervention. This seems to imply that they are the same species since other couples in Star Trek require a medical procedure in order to procreate.

Are they the same species or is this an oversight by the writers?

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    Relevant: scifi.stackexchange.com/questions/18622/… Jan 5, 2018 at 23:52
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    @ToddWilcox I always thought the Episode The Chase was created to address this issue, to indicate that all descendants of the Progenitor race had an innate compatibility...Then I watched Voyager...that messed up a lot of my theories about alpha quadrant races...*cough, cough* Seska... Jan 6, 2018 at 0:02
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    Come to think of it...maybe it's Cardassians that are so compatible as to interbreed with anyone who comes around...that would explain Gul Dukat's always accidental pregnancies and Seska's as well... Jan 6, 2018 at 0:09
  • m.youtube.com/watch?v=k4YpKo6IYtY
    – Ummdustry
    Apr 12, 2018 at 8:44

3 Answers 3


They don't necessarily have to be the same species to have compatable DNA as has been seen in other characters.

  • Spock was half-human and half-vulcan
  • B'Elanna Torres from Voyager was half-human and half-klingon
  • Deanna Troi from TNG was half-human and half-betazoid

There is also an article on Memory Alpha that details other Hybrid characters that have been seen.

Taken from the Memory Alpha article

Because of the common genetic ancestry of most of the species of the Milky Way Galaxy by way of the ancient humanoids, many species are able to interbreed with or without the help of genetic technology. In fact, Humans and Vulcans are quite similar. (TNG: "The Chase"; ENT: "Demons")

In some cultures, children who are born as a result of interspecific relations are rejected by the society of both races. For example, Bajoran / Cardassian hybrids were often rejected by both Bajorans and Cardassians. (DS9: "Indiscretion", "Return to Grace")

This would suggest to me that they are separate races and able to conceive either naturally or with some assistance from medical technology.

  • None of those species created offspring through entirely natural means. They all used futuristic medical technology. Jan 5, 2018 at 23:44
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    Deanna Troi mentions that she thought Humans and Klingons couldn't reproduce, but K'Ehleyr says that "the DNA is compatible...with a fair amouint of help" Jan 5, 2018 at 23:54
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    Seska certainly got pregnant by mistake...she was surprised to find out who the father was...and her partner was from the Delta Quadrant! Jan 6, 2018 at 0:04
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    @Quasi_stomach In the case of seska she was trying to have a child with a different species (chakotay, a human) possibly she took her "DNA comparability pill" or whatever and it just worked for the wrong father.
    – Ummdustry
    Apr 12, 2018 at 8:47
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    @Ummdustry That's assuming that the same measures would work for Cardassian/Human conception as Cardassian/Kazon unions Apr 12, 2018 at 20:25

In the natural world, different species can occasionally interbreed successfully. Take the mule, which is the offspring from breeding a horse and a donkey. There is even precedent for animals of different GENUSES (one level less related than species) interbreeding, for there is a recorded interbreeding of a domestic pig and a babirusa.


Conclusion: it may be possible even if they are different species if they are still closely related.

  • This is correct, however, those cross-species offspring are uniformly sterile. The bar for two biological groups to be considered the same or different species has always been that any offspring of two different species would not be able to have offspring itself. In other words, while Spock and B'lanna are both possible under the normal rules, as well as Seska's child, what matters on the species question is if B'lanna and Seska's children are sterile or not. I'm not aware of any offspring from Spock.
    – DocBon3saw
    Aug 4, 2020 at 22:40

I would not say they are, as that would imply that all cardassians are bajoran, when they are completely different species. I think it more likely that cardassians are like insects (what I suspect a humanoid bug would look like if made to look like a human) which would explain their behaviour in the early seasons of ds9. And as humanoid bugs, they would do anything they could for their colony, cardassia.

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    TNG: The Chase indicated that all of the humanoid species in the galaxy (one assumes this includes the Cardassians) share a common ancestor. And that ancestor isn't a bug
    – Valorum
    Oct 29, 2018 at 14:08
  • Most of this answers a different question but you do answer the question with "when they are completely different species". Could you edit in some more evidence to back up your claims?
    – TheLethalCarrot
    Oct 29, 2018 at 14:26

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