Looking only at genetic code, is it possible that there have ever been two genetically identical people who are not twins (or clones)? How many medically distinct human beings can their actually be?

I’m assuming that we’re only talking about biologically modern human beings. So the genes that make us human cannot be eligible for variation.

If we don’t include environmental factors and non-DNA genetic material, what is the actual number of genes that can vary from one person to another? Do we even understand the human genome well enough to make this kind of calculation?

I’m assuming from combinatorial math that it’s more humans than can ever exist through the course of the entire universe. But what is the actual number? If those genes are varied at random, how many people will it take before they say a 50% chance that two of them are identical? For example, it only takes 23 people to have a 50% chance that at least two of them have the same birthday.

Edit: I found an interesting article about the complications with trying to calculate this number. The number seems to be on the order of 10^(tens or hundreds of thousands)

  • Apeman42@lemmy.worldEnglish
    11·
    3 days ago

    I’m no scientician, but wouldn’t mutation mean that the possible number of gene combinations is constantly growing? And maybe even making previously non-viable permutations viable, which seems like it would really fuck with the math?

    • Skyrmir@lemmy.worldEnglish
      4·
      3 days ago

      There would still be a limit as long as the species was constrained to modern homo sapien. Mutating yourself out of the species would mean you’re no longer in the set of things.

    • gedaliyah@lemmy.worldOP
      1·
      1 hour ago

      I’m also no scientitian. I believe any mutations would have to be within the existing genome or else it would no longer be a biologically modern human.

      Let’s add the additional stipulation that we are not adding any meaningless genes. I know that there are a lot of them, but I’m just curious about what the math would look like and if we even have the knowledge about the genome to know which gene variations are meaningful.

      I’m thinking of the doppelganger thought experiment. Am I really the only person like me that has ever lived or will ever live? Or is it statistically possible that another genetically identical version of me could exist within the timeline of the universe (as I mentioned, with a 50% probability or better)?