Marvel Universe explains the origin of the Inhumans:

At the beginning of the Kree-Skrull War, millions of years ago in Earth time, the alien Kree established a station on the planet Uranus, a strategic position between the Kree and Skrull empires. Through their work at this station, they discovered that sentient life on nearby Earth had genetic potential invested in it by the alien Celestials. Intrigued, the Kree began to experiment on Earth's then-primitive homo sapiens by splicing Eternals DNA into Cro-Magnons.

So, Inhuman DNA is originally a cross breed of Eternals and Cro-Magnons.

Marvel Universe goes on to explain that the Inhumans historically selectively bred to strengthen their genetic pool and avoid unwanted mutations.

However, The Inhumanity storyline has shown us that there were people with Inhuman genes living on Earth without ever knowing their true nature.

Similarly, in the MCU, Skye only recently learned of her nature.

If Inhumans have different DNA than normal humans, why can they not be identified until after exposure to the Terrigen Mists?

  • 7
    just curious: how often do you think the average person has their DNA sequenced?
    – KutuluMike
    Mar 5, 2015 at 14:57
  • 4
    I do it at least once a week.
    – phantom42
    Mar 5, 2015 at 15:02
  • @MichaelEdenfield Well, we know that Skye had her DNA on file, so it seems like if something was abnormal, SHIELD would have noticed.
    – user1027
    Mar 5, 2015 at 15:25
  • @Keen Well, Fury said as early as Episode 1x02 that Skye"'s dangerous", maybe he knew more that Level 8 Coulson did (as Cap said, Nick can't help himself ;)). Her Comics counterpart is one of the few people with a Level 10 clearance, so maybe SHIELD did notice but SHIELD equipment was programmed to show only inconspicious DNA when it ran into hers.
    – BMWurm
    Mar 6, 2015 at 20:43
  • @Keen Probably not. She was hidden away due to the whole 0-8-4 fiasco when she was a baby - someone did know something, and it was covered up
    – Izkata
    Mar 7, 2015 at 2:57

1 Answer 1


Within the mainline comics continuity, the idea of the Inhumans is that, unlike "normal" mutants, they do not possess overt mutations from birth. Normal mutants possess an X-Gene, which activates on its own (usually at puberty), but for Inhumans, they merely possess the "genetic potential" for mutations to occur. This is what the purpose of the mist is: Terrigenesis is a conscious decision by the Inhumans to activate their powers.

Within the MCU, based on our very small sample, we can see a similar idea. Specifically, there are "extra molecules" in an activated Inhuman's DNA that clearly stand out as being non-human. However, pre-misting, this change does not appear in the DNA:

Fitz tells Skye that her newly taken DNA scans look notably different from her previous ones. Also, Simmons immediately sees the differences in Raina's DNA post-change, but does not see those same markers in the pre-misting DNA sample from Skye that Fitz swaps in.

I will note, however, that Simmons seemed to act a bit odd when looking at a scan of DNA from an inactivated Inhuman, which I immediately took to mean that there was something odd about it, but she only noticed it because she was looking for it. Logically, there must be some difference between the two, to account for the Inhuman "potential", but we don't know what that looks like. It may be extremely subtle.

So, the reason these people stay unnoticed so long is that their genetics are "close enough" to normal human DNA, at least pre-Terrigenesis, that no one noticed.

  • 1
    That's a good point about Simmons noticing something odd. She seemed to be studying it a little too closely until Fitz interrupted her.
    – Omegacron
    Mar 5, 2015 at 16:09
  • 1
    Fitz is technology, not biology, so I read it as him not realizing there's a marker that would tell Simmons that she's comparing the same sample to itself. For example, telomeres that are supposed to be shorter in the newer sample, but are instead exactly the same
    – Izkata
    Mar 7, 2015 at 3:00

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