Let’s say that a person has no aunts, uncles, cousins, or children. That person then dies. I am wondering if there is enough redundancy in the gene pool that the .1% of base pairs that make them unique, are still out in the gene pool in different combinations, in different people.
In other words, not all in the same person, just spread out among many people.
How about siblings? All of your DNA came from your mother and father originally. So if your parents had other children, some of “your” DNA is still out there.
The standard answer is that your children get half of their DNA from each parent. So, no, your “personal” DNA exists in you only.
JBS Haldane famously said that he would die to save two siblings or eight cousins, as the cumulative DNA of those groups of people would be equivalent to his own DNA. But, of course, it won’t ever be exactly the same. There is still a good chance of some small segment of information that you have that none of your relatives or descendants will have. It’s (relatively) random.
(Just my luck if my kid gets things like digestion and bone density from me…and looks, smarts, and deftness from my spouse! Nobody ever said the division of genes was gonna be fair.)
When we’re talking about personal DNA, I think there are two things to look at.
First, there are some random mutations that occur in each generation. These are not passed down by your parents, but were introduced either in the sperm/ovum or early in the developing embryo. Most of these mutations make no measurable difference in gene function/expression, but they do change the base DNA. These changes can only be passed down to your children, so a person without immediate family will have the only copy of those random mutations.
Second, there’s the issue of inherited DNA. These are genes that you’d expect to find elsewhere in the population, even if we’re talking about someone with no immediate family. I think some research said that everyone on the Earth is no farther apart than 20th cousins and we can certainly find someone closer than that for any given individual. While no one in the world will have your individual mix of genes, it’s a pretty safe bet that most of those genes do exist elsewhere in the population. In fact, most of the difference we wouldn’t see in the population are those random mutations from your parents and grandparents.
If we’re looking at base pairs, then the answer is “absolutely, but that’s useless”. There are only four bases, after all, so at any given location, there are over a billion people with each of them. It’s like the joke of an audience member requesting a particular song from a musician: “I don’t know that one, but you might like this one instead; it has a lot of the same notes”.
Much more meaningful would be to look at the level of whole genes.
The vast majority of the genes that the person carries will still be in the gene pool, yes. The only likely exceptions (assuming the person has no siblings or half-siblings) are going to be genes that became mutated in the specific ovum and/or sperm cell from which the person was conceived (or genes that were mutated in the ovum and sperm from which either parent was conceived, if the parent was an only child, and so on back through the generations, if they are all only-children).
The particular combination of genes that any individual carries can be expected to be unique (unless they are an identical twin) but very few if any of the specific individual genes are likely to be unique, and, of course, you do not pass on your unique combination to your children, just a more or less random selection of about half of your actual genes.
What makes your DNA unique is (mostly) not the genes themselves, but the specific combination of genes. For the most part, all these genes are in the gene pool. What you donate to your children is half of your unique set.
The exception to the “mostly” above is that you might have a mutation in your chromosomes that happened in your lifetime. If that mutation happened prior to the establishment of the germ cell line, or in the germ cell line, you could pass it on.
Furthermore, while you donate whole chromosomes, they aren’t quite the ones you started with, due to crossovers. For each chromosome pair, you donate one of the two … sorta. Before that donation happens, the two chromosomes in the pair do any number of “crossovers”, where part of one gets exchanged for the same part of the other. (Usually the same … if not, it’s one of the kinds of things that can cause the mutations mentioned above. But let’s ignore that here.) So, your child will get genes you have, but a different set of them on a given chromosome than what you originally had. Mainly, this mixes things up for the next generation.
So, what makes you unique isn’t the genes in your DNA as much as the specific combination of genes in your DNA. You pass some of that to your children.
Other people will have most of those genes (all but the ones you or your immediate ancestors “invented” by mutation), but nobody will have quite the same set you have, and the farther away from you by “blood”, the less like your particular set theirs will be.
Yes, unless you happen to have a mutation, but even then there’s a chance that someone else also has that mutation.
All your genes (except for mutations) came from your ancestors. But it’s not uncommon for some genes (or alleles, really) to multiply so you may have 3 copies of a particular gene wile your parents only had 1.
A related topic is “kin selection”. (See Sociobiology by E. O. Wilson, but I think plenty of others have written about it too.)
The classical idea is that a gene will propagate itself in the population if that gene confers some selective advantage to its bearer. But “kin selection” suggests that a gene may propagate itself (or rather, others like itself) in the population if it confers selective advantage to persons, other than the bearer, who carry similar genes.
In other words, a gene may propagate in the population if the bearer somehow helps his close relatives survive, those being the people most likely to bear the same or similar genes. For example, altruistic behavior (helping others, even possibly at one’s own expense) is theorized to work this way.
The OP has deliberately rules out all sorts of “close” kin in his hypothetical. But at some distance, it is argued (as noted by dracoi, above) that we are ALL kin, at least a little bit.
And the sort of behavior that evolved because it tends to support close kin can also be a more general behavior towards others too. Thus, the “social” animals like bonobos, dolphins, doggies, humanses may even behave helpfully towards others who aren’t even the same species. One can find umpteen cute glurgey examples of this in the inside pages of the supermarket tabloids.
If it happened in “your” lifetime, it will only be in one or a few cells: the one the mutation happened to, and any that budded off that one. Unless those cells are ova or sperm producing cells, you won’t pass the mutation on. If you have a mutation throughout your body, it happened in one of your parents germ cells.
The thing is - mutations happen all the time. So your particular combination, with your personal mutations? Not surviving.
Your parents’ DNA, with their personal mutations? Not unless you have siblings.
Grandparents… your cousins. and so on.
You might think of it like - if I die lonely, does my surname die too? How unique is it? If it is a weird spelling that happened on Ellis Island, maybe. If it’s a surname that goes back to the Norman invasion, odds are you’re competing with a million other Jones or Martins or Schmidts.
There’s always pure dumb luck, that when the genes were handed out 50-50, only one of that generation got that copy so you are the sole carrier. You can calculate the odds, but it’s analogous to flipping a coin and getting 50 heads in a row. There are 2^50 choices for flipping a coin 50 times in a row, and each time you do, you end up with only one of those quadrillion choices…
I have to take exception to this. This assumes that each of the four bases at every location in the genome are equally likely, which is obviously not true. If it were, there would be no natural selection and no evolution. There are many loci in the genome where one base is strongly preferred over the other three, where, indeed, nearly everyone will have exactly the same base. Indeed, this is a common measure used in population genetics to determine which bases are critical for a given function. If you’re looking at a gene, and nucleotide 46 is a C in 99.3% of the population, the odds are pretty good that that C does something really important for the organism.
Yes, but the OP specified his unique DNA, by which I took him to mean that portion of his DNA which isn’t universal to the species, or to almost all of it.