Something Bizarre about this movie.....

Is that KHAN (and his followers) are in it. They are not shown in the movie but they would be living on the same planet (Earth) during the events of the movie albeit on different parts of the planet. Kirk could have tracked down a younger Khan and killed him maybe. Doing so should save his son because Khan indirectly killed his son by stealing the genesis device. It was supposed to be a secret but the metaphorical cat was out of the bag and that resulted in the Klingon villains of Star Trek 3 trying to get it, and his son dies on the same genesis planet that Khan created in a final attempt to kill Kirk in the previous movie. He could have tracked down and assassinated younger Khan but then the events of Space Seed would not have happened.

Time travel does nothing but create messes.