ADAM, when used alongside its byproduct, EVE, allowed the user to rewrite their genetic code and empower them with untold enhancements or abilities.

Source: https://www.cbr.com/important-bioshock-lore/

Now that Samus' DNA is revealed to be the only existing hybrid of human and Metroid genetic code, she poses a significant threat to the peace and safety of the galaxy.

Source: https://gamerant.com/metroid-halo-controversial-story-choice-new-protagonist/

Upon the collapse of the Isu civilization, some of the most influential Isu submitted their genetic code into the human gene pool to be reborn at a later date.

Source: https://gamerant.com/assassins-creed-mirage-basim-characteristic-sage-loki/