3 ms·

They are not identical. Both born with different physical problems. How do you call that identical?

apothegm 3y ago
Twins can be born with the same genes (because they originated as a single embryo that split), or with different genes (they originated as two separately fertilized embryos). The former are considered identical twins even if you can tell them apart. They’re genetically identical, which scientists find useful in teasing out nature vs. nurture hypotheses. They especially like to compare them against twins with different genes — who are called fraternal twins even if you can’t tell them apart.
- iamleppert 3y ago
  Isn’t it obvious they aren’t physically identical? They have the same genes but are not identical!
  - astura 3y ago
    This is where English terms we use is very imprecise and can be confusing. English calls twins that were once the same zygote "identical" no matter what they look like or what happened after the zygote split.
  - SiempreViernes 3y ago
    The term is being used in reference to their genes, not their appearance.
    - INTPenis 3y ago
      I'll mirror what someone else said, have they actually sequenced them? Clearly a lot of changes happened at a very early state, mutations, so why should we expect their genetic makeup to be identical?
      - adolph 3y ago
        Also: In animals and human chimeras, this means an individual derived from two or more zygotes, which can include possessing blood cells of different blood types, and subtle variations in form (phenotype). https://en.wikipedia.org/wiki/Chimera_(genetics) https://en.wikipedia.org/wiki/Chimera_(genetics) For example, in 2002, news outlets reported the story of a woman named Karen Keegan, who needed a kidney transplant and underwent genetic testing along with her family, to see if a family member could donate one to her. But the tests suggested that genetically, Keegan could not be the mother of her sons. The mystery was solved when doctors discovered that Keegan was a chimera—she had a different set of DNA in her blood cells compared to the other tissues in her body. https://www.scientificamerican.com/article/3-human-chimeras-that-already-exist/ https://www.scientificamerican.com/article/3-human-chimeras-...
      - abejfehr 3y ago
        it’s almost certainly not identical now, it just used to be at conception
  - pbhjpbhj 3y ago
    "Identical twins" is not a description of the twins character, specific physical features, behaviour, nurturing. Instead, 'identical twins' is a noun-phrase meaning two children from a single zygote, ie 'monozygotic'. It does not mean "twins who are literally identical"; though you could think of it as twins who are genetically indistinct. I'm a physicist with no biology qualifications, but it just sounded to me like you may have misunderstood the linguistic meaning. Apologies if I was wrong about that.
twobitshifter 3y ago
identical means genetically identical.
- pfdietz 3y ago
  Well, aside from somatic mutations arising during development.
mkl 3y ago
https://simple.wikipedia.org/wiki/Identical_twins https://simple.wikipedia.org/wiki/Identical_twins

Twins can be born with the same genes (because they originated as a single embryo that split), or with different genes (they originated as two separately fertilized embryos). The former are considered identical twins even if you can tell them apart. They’re genetically identical, which scientists find useful in teasing out nature vs. nurture hypotheses. They especially like to compare them against twins with different genes — who are called fraternal twins even if you can’t tell them apart.

iamleppert 3y ago
Isn’t it obvious they aren’t physically identical? They have the same genes but are not identical!
- astura 3y ago
  This is where English terms we use is very imprecise and can be confusing. English calls twins that were once the same zygote "identical" no matter what they look like or what happened after the zygote split.
- SiempreViernes 3y ago
  The term is being used in reference to their genes, not their appearance.
  - INTPenis 3y ago
    I'll mirror what someone else said, have they actually sequenced them? Clearly a lot of changes happened at a very early state, mutations, so why should we expect their genetic makeup to be identical?
    - adolph 3y ago
      Also: In animals and human chimeras, this means an individual derived from two or more zygotes, which can include possessing blood cells of different blood types, and subtle variations in form (phenotype). https://en.wikipedia.org/wiki/Chimera_(genetics) https://en.wikipedia.org/wiki/Chimera_(genetics) For example, in 2002, news outlets reported the story of a woman named Karen Keegan, who needed a kidney transplant and underwent genetic testing along with her family, to see if a family member could donate one to her. But the tests suggested that genetically, Keegan could not be the mother of her sons. The mystery was solved when doctors discovered that Keegan was a chimera—she had a different set of DNA in her blood cells compared to the other tissues in her body. https://www.scientificamerican.com/article/3-human-chimeras-that-already-exist/ https://www.scientificamerican.com/article/3-human-chimeras-...
    - abejfehr 3y ago
      it’s almost certainly not identical now, it just used to be at conception
- pbhjpbhj 3y ago
  "Identical twins" is not a description of the twins character, specific physical features, behaviour, nurturing. Instead, 'identical twins' is a noun-phrase meaning two children from a single zygote, ie 'monozygotic'. It does not mean "twins who are literally identical"; though you could think of it as twins who are genetically indistinct. I'm a physicist with no biology qualifications, but it just sounded to me like you may have misunderstood the linguistic meaning. Apologies if I was wrong about that.

twobitshifter 3y ago

identical means genetically identical.

pfdietz 3y ago
Well, aside from somatic mutations arising during development.

mkl 3y ago

https://simple.wikipedia.org/wiki/Identical_twins https://simple.wikipedia.org/wiki/Identical_twins