Assuming an average, fully developed adult man, what sort of changes could be made to his genome that would have a noticeable effect on his mind or body? To the best of our current scientific knowledge, that is. I know we don't know what a lot of genes are for.

To be specific, I want to know if you could change the physicality of a person, as in, their strength, stamina, and metabolism, and wether or not you can change a person's personality, most importantly their focus, or at least their urges.

Other information that I know:

  • Most genes responsible for features are only relevant during the development of those features, and changing them post-development would have no effect of the person who had the change. For example, changing genes for bone structure would have no effect on somebody with developed bones. Their children might show a change, though.
  • Editing the genome of an adult is difficult due to the number of cells that have to be edited. Assume this has been taken care of.

BONUS POINTS (You don't have to) IF

  • You can link to a research paper describing a gene and its effect on an adult.

Also, does this question qualify for the tag?

  • $\begingroup$ I would say that it's fine for the hard-science tag, but be sure to add it before you get answers. $\endgroup$
    – HDE 226868
    Mar 24, 2016 at 23:44
  • 1
    $\begingroup$ Are you looking for a specific TYPE of change? Because I'm fairly certain that simply changing half of his DNA to match that of a banana would have some kind of impact on him, although I imagine the result would not be very appealing. $\endgroup$
    – ChronoD
    Mar 25, 2016 at 0:18
  • $\begingroup$ @ChrisG Changes to the physicality of the person, like their strength, stamina, and metabolism, as well as changes to the mind and personality. Although I'm pretty sure if you replaced half of a human's DNA to match that of a banana you'd have a concerningly fruity hermit. $\endgroup$ Mar 25, 2016 at 1:22
  • $\begingroup$ I took off the hard-science tag because two answers already posed are science-based and well received. $\endgroup$
    – JDługosz
    Mar 25, 2016 at 2:14
  • $\begingroup$ @JDługosz Thanks, further questions from me will strive to avoid having to be edited like that to save moderators micromanagement $\endgroup$ Mar 25, 2016 at 2:18

3 Answers 3


Gene therapy is a real thing, and you can read about the various changes that are contemplated and realistic enough to research.

It has trouble actually working in a living body when it seems obvious (replace a defective copy of a protein making gene) and seems ok in a cell culture. So doing something like that in a large scale is probably far more difficult to get to work.

Assuming advanced tech can replace genes in living cells that are part of tissue and not otherwise damage things, what can happen? Consider what happens if you update code for a liver enzyme, and it's not a liver cell: nothing! Not all genes are used in all cells.

What happens if you change the code that controls limb growth during development? Nothing! That program is run as an embryo and never again. It would affect his children.

Now some "layout" is done during healing. If you change the code for growing skin— how the dermis lays out all the different cell types to produce connective tissue, blood vescles, glands, and skin organs, then to the extent that the body can regrow missing skin, it will produce the new design. Routine replacing of the epithelial cells will only involve the code for producing those cells, not any different kind of cell or layout.

Changing behavior and urges: look at hormone production. What can be done with drugs? Any drug's effect can be produced directly with reprogramming the cells. Change the behavior of dopamine receptors by jamming them open? Just alter them instead, or just produce the same drug directly in the cells!


Your entire body cycles through cells many times throughout your entire life. If you completely rewrote your DNA, then changes would gradually appear as cells replaced themselves.

Your stomach lining, for example, completely cycles every three days or so. Change that, and you might be able to digest things differently.

Could you change the rate of change? You might get effects to appear faster.

Every time your DNA replicates, the end pieces (telomers) don't and the copy is a tiny bit shorter. That adds up over the years. If you replace your DNA with long fresh strands, then you've just become immune to old-age.

  • $\begingroup$ Welcome to the site Omniwombat $\endgroup$
    – James
    Mar 25, 2016 at 1:45
  • $\begingroup$ See my comment to the other answer. Why would changes only show up after a cell divides, if it already had the DNA? I don't know if digestive enzymes are secreted by the lining or by special glands, but whichever cells are doing it, if they were reprogrammed they would produce the altered enzyme immediately. $\endgroup$
    – JDługosz
    Mar 25, 2016 at 2:13

Continuing with Omniwombat's theme that most (all, except brain cells in cerebral cortex, they say) of your body cells are replaced with newer ones, some of the most visible changes you could produce with editing your dna are:


Since skin cells are replaced every 4 weeks (reference), any change related to the color, thickness and texture of your skin would be visible after a month or so at most. I don't know if you can get away (survive) with adding snake-like scales or turtle-like body armor to yourself, but you can get away with making yourself hairless (you won't die directly of hair loss, but there might be indirect implications).

Endocrine System

Hormones control a lot of our behavior and internal functionality. Twerking with your pituitary, adrenal and thyroid glands to increase/decrease the release of their hormones would produce a marked difference in your behavior and body shape/functionality.

  • $\begingroup$ So you mean that the last progenitor cells have been changed but the terminal epithelial cells were not, so don't show the new DNA until they are replaced? And why would this make it want to grow different structures in a completed body, rather than only affect the internal metabolism of the cell? $\endgroup$
    – JDługosz
    Mar 25, 2016 at 2:09
  • $\begingroup$ And your poor little taste buds, who will never come back 😢 $\endgroup$ Mar 25, 2016 at 15:15

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