Very interesting game! An DNA-based ending-hunting snake game is a very cool concept, and the fantastic artwork with each ending was very nice. The text for each ending I also found quite funny. Good job on those!
Speaking of the text at the endings, though, it seems that when replaying the game after restarting, new ending text is appended to the last ending’s text rather than replacing it. It’s probably due to some plus-equals (+=) signs being where some equals signs should instead be when setting the ending text.
Also, I agree with the other commenter that it was somewhat confusing to work towards certain endings. I think it would be helpful for endings to tell you what dominant genes led to them, so that the player will know what combinations they’ve already tried. Additional clarity in regards to how exactly an ending is calculated might also be nice, or more tips for picking genes.
Overall had fun with the game and thought the concept very interesting. Good job!