At the start of Man of Steel, we see Jor-El imbuing Kal-El with the Kryptonian Codex.

The Codex is an ancient Kryptonian artifact that defines the genetic makeup of the artificially incubated babies on the planet.

I will elaborate on this: he holds back for most of the movie, he never had to push himself at all, ever. Once he beat the World Engine, he came back and proceeded to mush Zod and then kill him. Despite Zod being a soldier made by the Codex, and Kal-El wasn't made from the Codex, but contained the Codex.

Does this Codex being in the DNA itself of Kal-El make him stronger than other Kryptonians?

Does it have any other effect on Kal-El?

  • 5
    Why would you think it did? Wasn't he getting his rearend kicked most of the movie?
    – Radhil
    Feb 16, 2017 at 13:24
  • Ok I will elaborate in the question.
    – JamesD
    Feb 16, 2017 at 13:44

3 Answers 3


If having the codex has any effect on Kal-El at all, there's no indication of that in the movie.

Kal-El is Superman because he grew up on Earth, under our yellow sun. Zod and the other Kryptonians become powerful under the light of the sun, but it's not the same as having grown up under its influence. This is the main reason Kal-El is so much stronger.

Beside being implied and generally understood, there are lines in the movie that support this:

  • Jor-El believes that his cells will "drink the radiation" from the sun, making him a "god".

Jor-El: Did you find the world?
Lara Lor-Van: We have.
Kelex: Orbiting the main sequence yellow star, just as you said it would.
[Kelex shows them earth]
Jor-El: It’s a young star. His cells will drink it’s radiation. It’s a seemingly intelligent population.
Lara Lor-Van: He’ll be an outcast, a freak. They’ll kill him.
Jor-El: No, he’ll be a God to them.

  • Jor-El is surprised when he meets the adult Clark, as he's even stronger than he would've predicted. This is evidence of how growing up on the planet has amplified the effect.

Jor-El: You've grown stronger here than I ever could've imagined. The only way to know how strong, is to keep testing your limits.

  • Zod recognizes that Kal-El has adapted to "Earth's ecology". This is contrasted to the Kryptonians, who wear environment suits when they first arrive.

General Zod: You’ve spent a lifetime adapting to earth’s ecology but you never adapted to ours.


Superman had been absorbing yellow sunlight for 33 years, while the other Kryptonians including Zod, were new to the Earth's environment and thus had only had time to absorb a smaller amount of energy.

  • Welcome to SFF! Do you have any contextual evidence support this, or is it just your guess? Take a minute to view our tour page and see what kind of answers we are looking for.
    – Skooba
    Mar 4, 2017 at 14:55
  • But how does this relate to the Codex? This is what the OP is asking about. Mar 4, 2017 at 15:53
  • This is a "no". He gets his strength from this, not the codex. This is definitely the case in the movie.
    – DCShannon
    Apr 12, 2017 at 0:29

The codex was essentially base level genetic information, which, frankly, could be carried by any living being. Getting stung by a bee, for instance, introduces trillions of bits of DNA coding from that specific hive into your system, but it won't make you any "stronger". I'm guessing Jor-el coded it into his son's cells so the genetic legacy of the planet could live on. While not impacting his physical abilities, it likely means Clark is walking around with a base template for millions of future generations within his DNA.

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