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Semi-Identical Twins Discovered

daftna writes in with a story from Nature about a pair of twins who are neither identical nor fraternal: they are semi-identical. Researchers discovered twins who share all of their mother's DNA but only half of their father's. Both children are chimeras — their cells are not genetically uniform, but include a mix of genes from two separate sperm cells that fertilized a single egg. This is, apparently, not as rare as one might think; but the resulting fetus is rarely viable. This report marks the first known incidence of two half-identical twins resulting from a double fertilization.

16 of 224 comments (clear)

  1. Sounds like mom was a busy girl. by alcmaeon · · Score: 5, Funny

    Subject says it all.

    1. Re:Sounds like mom was a busy girl. by maxume · · Score: 5, Funny

      Problems with your sperm count? (lots of guys have more than, ya know, one. Harr).

      --
      Nerd rage is the funniest rage.
    2. Re:Sounds like mom was a busy girl. by Anonymous Coward · · Score: 5, Funny

      Inconceivable!

  2. Discovery Health "I'm my own twin" by Marxist+Hacker+42 · · Score: 5, Interesting

    We're finding new chimeras every day, now that DNA testing is becoming more common. Discovery Health even had a program where genetic testing showed a mother's children to be the product of her BROTHER and her husband; though she had no brother. Turned out she was a hermaphrodite- some of her cells, including her EGGS, were male- a fraternal twin that had been absorbed early in the gestation process.

    --
    SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.
    1. Re:Discovery Health "I'm my own twin" by Anonymous Coward · · Score: 5, Interesting

      Could a similar event lead to a virgin giving birth? News of such an event could be of Biblical proportions.

    2. Re:Discovery Health "I'm my own twin" by Starburnt · · Score: 5, Funny

      More importantly, Slashdotters may now be able to reproduce.

      That could be of Biblical proportions.

    3. Re:Discovery Health "I'm my own twin" by JeanPaulBob · · Score: 5, Informative

      No, "virgin" was not "indisputably" a mistranslation. And it is most certain that your "young woman" is a poor translation--to my mind, worse than "virgin".

      The issue is not with the New Testament; there is no question that Mary is reported to have been a virgin in the New Testament. The issue originates with the Septuagint, the Greek translation of the Old Testament produced by Jews before the time of Christ, and it has to do with the translation of Isaiah 7:14, an ostensibly Messianic prophecy. (The Septuagint was the translation used by New Testament writers.) It translates the Hebrew "almah" with the Greek "parthenos". Parthenos almost always means "virgin", while almah has a slightly different but overlapping semantic range. It's closer to "maid, unmarried girl, young woman of marriageable age". (Your "young woman" leaves out the unmarried/of marriable age implications.) Culturally speaking, an almah most likely would be a virgin--that would be the strong expectation, and it's enough to make "virgin" a connotation of "almah". While parthenos is not a precise translation, it is not a mistranslation. At the very least, not indisputably so. My goodness, man, just read the Wikipedia entry on almah and follow the references! This is not obscure information.

      Sure, if you limit the meaning of "almah" to "young woman", it makes for a better game of "Hee hee, look at the silly Christians," but if you're interested in honest scholarship, you'll have to open your mind a bit.

    4. Re:Discovery Health "I'm my own twin" by Ravon+Rodriguez · · Score: 5, Insightful

      Turning water into wine, walking on water, bringing the dead back to life... and It's the translation of the word "virgin" that you have a problem with?

      --
      Jesus loves me, he loves me a bunch, because he always puts Jiffy in my lunch.
  3. DUP!! by dustball23 · · Score: 5, Funny

    This story was already posted!! Oh, no, wait...

    1. Re: DUP!! by Black+Parrot · · Score: 5, Funny

      We don't get dupes, we get semi-identical posts.

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      Sheesh, evil *and* a jerk. -- Jade
  4. They need a different term besides "Chimera" by The-Bus · · Score: 5, Funny

    I understand it's mythologically correct to use the term "chimera" but whenever I hear it I always envision something else: a ghastly soulless beast with an iron heart, breathing fire out of a cavernous tooth-lined maw, crushing entire houses under gigantic feathered elephant legs; a scaled, whiplike tail kicks up ashy dust clouds as its dragged for miles behind this monstrocity.

    No matter how many times I hear the biological equivalent of the term (which is never as exciting) I'm always let down. I always think some giant monster has been discovered, or someone turned into this monster, or geneticists have new clues as to the cause of this monster.

    It's a bit annoying once I'm letdown but for a precious few seconds I'm always aghast in wonder.

    --

    Small potatoes make the steak look bigger.

  5. No problem by EmbeddedJanitor · · Score: 5, Funny
    Problems with your sperm count?

    No I can count up to five, even with one hand busy!

    --
    Engineering is the art of compromise.
  6. Re:Serious question by reverseengineer · · Score: 5, Informative
    Well, this case is primarily interesting in the sense of "this thing that very rarely happens, it just happened." The main scientific benefit is that further light is shed on the mechanisms of human reproduction. Obviously, the outlines of that process are well-known, but there's still a lot of uncharted territory when it comes to the non-normal functioning on this process. Reproductive biology is an area where animal models (even in other primates) tend to translate rather poorly to human beings, and is of course also an area with ethical limits on human experimentation. Conceivably, learning about cases like this can advance knowledge about things like infertility and birth defects.

    There's actually an interesting story, almost the flip side of this rare case in humans, running now in the New York Times about marmosets, in which a form of chimerism is quite widespread:

    One of the most surprising results of the study is that over half of male marmosets have chimeric sperm. Dr. Ross and her colleagues discovered cases in which the DNA of male marmosets turned up in babies supposedly fathered by their fraternal twins. In other words, the sperm came from one male, but it had the DNA of the male's brother. A paternity test would show that the baby's genetic father was actually its uncle. The scientists were not able to isolate DNA from marmoset eggs, but they did find that 2 out of 21 marmoset ovaries were chimeric. It's possible that a female marmoset can give birth to nephews and nieces.
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    "FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
  7. Why this is notable: Cortical reaction by wile_e_wonka · · Score: 5, Informative
    I thought I would note why this doesn't happen all the time in humans (in some mammals it is common for an egg to be able to be penetrated by more than one sperm).

    According to my anatomy textbook, after the spem digests its way through the zona pellucida:

    The plasma membranes of the sperm and oocyte then fuse, and the sperm nucleus is engulfed by the oocyte's cytoplasm. This fusion induces the cortical reaction, wherin granules in the oocyte secrete enzymes into the extracellular space beneath the zona pellucida. These enzymes destroy the sperm receptors on the zona pellucida, preventing any other sperm from binding to and entering the egg.

  8. Re:wow, that must be embarassing by The+One+and+Only · · Score: 5, Funny

    Maybe some women should try for this to achieve notoriety and advance the cause of science...

    And the plot for the next gang-bang porno suddenly comes into view.

    --
    In Repressive Burma, it's not just your connection that dies. slashdot.org/comments.pl?sid=314547&cid=20819199
  9. On intersexuality by asninn · · Score: 5, Insightful

    Imagine living a life where you are called "a very special and wonderful person", but no personal life or even ability to enter either public restroom without people looking at you dubiously.

    Do you really think that this is the biggest problem intersexual people will ever face in their life? If yes, you seriously need to read up on these things a bit.

    First of all, as a disclaimer, I'm not intersexual myself, but I'm interested in inter- and transsexuality and know a couple of people who are. Most of the intersexuals I know had a gender surgically assigned to them after birth, too (female, FWIW; as doctors say, "it's easier to dig a hole than build a pole"). But you know what? Neither of them is happy.

    In fact, the *exact opposite* is true. *Every single* intersexual I've talked to or heard about has said the same thing so far - that doing so is, essentially, butchering, a traumatic experience that will haunt you for your entire life. Even in these times where sexual reassignmet surgery is not impossible anymore, the results are far inferior to anything that nature came up with (if you can even afford the whole procedure!), and the psychological problems associated with having your body mutilated after birth are just as serious.

    What really needs to be done when an intersexual child is born is really easy: bloody leave them alone. The child will eventually grow up and be able to make their own decisions; if they decide then that they really belong to one gender, it's not too late to do surgery etc.. What's more, it might well be that the child decides that they're really male - contrary to popular opinion, "intersexual" and "transsexual" do not mean "a guy who wants to become a chick".

    But there's also a decent chance that the child will say "I'm happy the way I am", and who's to say that that's not within their rights? If the only reason you can come up with is that there might be confusion over which restroom is appropriate, well... I'm sorry, but that isn't quite enough.

    What's more, when you're talking about things like restroom usage, you make a very fundamental mistake: you look at what other people and society in general will see the child as, rather than what the child themselves thinks. But it's the child who will have to live with their body; the idea that society has a right to say "you don't fit into our binary system, so we'll cut up your body and then pretend that you do (even though you really still don't)" is outrageous.

    FWIW, BTW, another fundamental mistake that's often being made is the assumption that it's even possible to reassign gender - that is, the actual gender that someone identifies as, as opposed to their physical sex. One of the reasons why intersexual people were mutilated in the past and raised as girls is that doctors (wrongly) believed that if you just cut off everything that was non-girly and if you just put the child into a dress and told them they were female, they'd really believe it and grow up as a normal, well-adjusted *woman* - but in reality, it doesn't work, and never has.

    Of course, I do understand that there are no ulterior motives - doctors, parents etc. really are trying to help intersexual children. But it's also important to realise that it's not working and that the only thing you're doing is CAUSING harm, not preventing it.

    So, although this has little do to anymore with the original TFA, just let me say this: leave intersexual children alone, and let them make their own decisions when they're old enough. Until then, be tolerant, be honest, explain to them why they're different, and explain that it doesn't make them worth less or anything like that. That's the ONLY way you can actually help them.

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    butter the donkey