Wondering if you should stab Gene in High on Life? There is just one opportunity for you to do this rather despicable deed, which comes as soon as you return to the house after your first proper mission in the Slums.
There's a similar moment in the kill 5-Torg. However, the difference here is that your knife has wanted to plunge into Gene's sides so much that he never shuts up about it. Again, you may be thinking there are consequences for doing so, such as losing a valuable ally willing to help you on your journey, but it's far more mundane than that.
To stab Gene in High on Life, interact with him after the knife requests that you stab him. Initially, Gene complains that you've just driven your knife into his side, but there are no long-term repercussions for shanking him. Gene is still alive and helps you throughout the game as if nothing happened. You also get the Don't Knife the Hand That Feeds You achievement. If you want this achievement, make sure you plunge the knife into his flesh before leaving the house, as this is one of the few missable achievements.
And that's why you should probably stab Gene in High on Life. Even if these moments don't have any real bearing on the ending or even unlock the best PC games of all time to see if there's something else that tickles your fancy.