22 thoughts on “Maybe Even Identical Twins Aren’t Perfectly Genetically Identical

  1. Benjamin Ledford

    Yes, I’ve been learning over the last year or so that genetics is a lot fuzzier than my earlier impression of it. For example, there is genetic variety within each of us in our different cells and our genes can change over the course of our lives as they degrade. Also, apparently genetics are not as rigidly determinative of our physical characteristics as I had thought. And most of our ancestors don’t pass any genes along to us after several generations, to the point that if you back beyond 200 or 300 years we can’t even identify family relationships through DNA. All very interesting I suppose.

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    1. Yeah, when I first heard that illness or stress or other environmental factors can “change our genes,” I thought, “Well, that pretty much invalidates the whole thing.” Obviously it’s not quite that simple, but still ….

      A while back I posted a link to a finding that people’s cells can show genetic material from organ donors (genetic material not in the donated organ, that is).

      But I don’t quite understand what you are saying about that 2-300 year horizon. Where else are we going to get genetic material except from our ancestors?

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      1. Benjamin Ledford

        We get it from fewer of our ancestors. šŸ™‚

        The premise is that as you go back in time we have more and more ancestors, which means that each ancestor contributes less to your genetic makeup. So you get 1/2 of your genes from each of your parents, but only 1/4 from each of your grandparents, 1/8 from your great grandparents, etc.

        But they’re also not passing along those genes in evenly distributed portions. So the 1/2 of your genes that you got from your mom isn’t guaranteed to have equal parts genes from each of your grandparents, even less so your great grandparents. So if you go 5 generations back, some ancestors are contributing more than 1/32 of your genetic makeup, while others are virtually undetectable. If you go back 500 years, you have 65,000 direct ancestors in that generation, but most of them didn’t pass any genetic information to you. Their genes got crowded out before they made it that far.

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      2. Well, that makes perfect sense.

        I guess that is why, when you get one of those novelty DNA tests, all they can tell you is statistically where in the world the DNA that was found in your sample came from. You could get different results with a different sample from the same person. Or so I understand it.

        Of course, if you go back thousands of years, probably some of your ancestors were marrying their cousins anyway. So there might be some redundancy built into the system.

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      1. I don’t mind people talking to each other in my comments section. In fact, it’s fun.

        Scyenze is how Bookstooge spells the word when it’s treated like a religion. This is distinguished from science, which is, you know, just figuring out the natural world but not the be-all and end-all of everything ….

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      2. Bookstooge isn’t allowed to make up words. šŸ˜€

        Ah, who am I kidding. šŸ¤ 

        No wonder the confusion surrounding science being the end all, be all. God’s hidden hand is behind all of it. That’s what I believe and that Jesus Christ is my personal savior. I’ll tell anyone that asks me!

        I’ve seen enough things in my day to know exactly what’s going on and it trails of of this as well, also keeping in mind that they aren’t even born identical and then there are environmental factors that can change their DNA:

        Now, suppose you could hook one keyboard and mouse into identical computers, same exact software, same exact hardware . . . How long would it take before you simply couldn’t type or click the same thing on both the computers because of a difference in output?

        Also, have you ever heard of people that have different DNA in different parts of their body? Not sure if I read it in a fiction book or not . . .

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      3. Thanks for this comment.

        I have no doubt about the DNA in different parts of the body, but I am not knowledgeable enough to comment. It is such a hugely complex area of study. Unfortunately it’s one of those areas where even the experts don’t know much, yet the lay person is familiar with the term and we tend to think we know more than we do.

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