Like full blooded Vulcans, the hybrid Spock is driven by the urges brought on by pon farr. Can hybrid Vulcan/Humans reproduce, or are they like horse/donkey hybrids on Earth, physically willing, but biologicaly unable to create offspring?

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    If one of them is Jolene Blalock, I'd be willing to try. For science.
    – John O
    Commented Aug 14, 2012 at 3:29
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    As a side note, female mules can give birth to offspring, but it is rare. There has, however, been no known cases of a male mule siring an offspring. Commented Aug 14, 2012 at 4:19

4 Answers 4


In the Star Trek novel "Yesterday's Son", Spock discovers that he fathered a son with Zarabeth when he was stranded in the past in the 'All our yesterdays' episode. So a male hybrid produced by a Vulcan male / Human female can be fertile with humans.


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    Zarabeth was humanoid, but not human. She was Sarpeidonian. Commented Jan 23, 2016 at 16:38
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    Human or not, this does tell us that Spock was fertile
    – Gnemlock
    Commented Dec 21, 2017 at 6:24

No limitations have been mentioned for hybrids. There are some canon cases of hybrids having offspring:

In The Drumhead, crewman Simon Tarses is put on trial and suspected of having falsified his origins as 1/4 Vulcan, when he is in fact 1/4 Romulan (to which he pleads the fifth seventh). Since we know that Romulans are an offshoot species of Vulcans, odds are that their genetics are relatively similar for reproduction.

Crewman Daniels was also of multiple origins, one of which was Vulcan, suggesting that interbreeding is quite extended by the 31st century.

In the non-canon part, a few lines were dropped from Star Trek IV where it would have been revealed that on the Genesis planet (in III), Saavik had had sex with Spock (since he was going through a few instances of pon farr thanks to the accelerated aging), and later took a maternity leave.

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    Hopefully it was the Kirstie Alley Saavik.
    – iMerchant
    Commented Jun 8, 2016 at 16:36
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    Actually, Simon Tarses is direct evidence that human/vulcan hybrids can have offspring. Not because he is 1/4 Romulan and that Romulans are closely related to Vulcans. But because he claimed he was 1/4 Vulcan, and everyone he interacted with in the Federation, including doctors, believed him.
    – Ellesedil
    Commented Jun 8, 2016 at 16:40
  • @iMerchant Kristie Alley was in Star Trek II, not in III. But yeah.
    – MPelletier
    Commented Jun 8, 2016 at 17:10

Kirk's son with a Romulan/Klingon in the book universe was sterile. They hint that one biology is dominant. Spock is never called a human and B'elanna is always called a Klingon or hybrid.

So, unlike a mule, which is a blend, Star Trek humanoid hybrids seem to be more like a phenotype than true hybrids.

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    Which book had Kirk having a son with a Romulan or Klingon?
    – FuzzyBoots
    Commented Mar 19, 2015 at 12:25
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    There are Star Trek books? I thought there were only Tv shoes an movies...
    – Rincewind
    Commented Jun 8, 2016 at 15:53

In the Star Trek novel "Yesterday's Son", it's revealed that Spock and Zarabeth (seen in the TOS episode All Our Yesterdays) had a child named Zar.

From the blurb:

"The starship Enterprise must protect the Guardian – or destroy it. But Spock has already used the portal to journey to the past. On the planet Sarpeidon, 5,000 years ago, Spock knew a beautiful, primitive woman. Now he has gone back to meet his son!"

The cover even sports a picture of the boy in question:

enter image description here

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