How different can genetically identical twins get?

  • Thread starter Simon Bridge
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In summary, this article discusses the idea that DNA does not necessarily lead to a specific appearance, and that epigenetics may play a role. It also discusses the idea that twins may not be as genetically identical as we might think, and that there is a tendency for children to learn to look similar as they grow up.
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Simon Bridge
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Articles like this one tend to lead to speculation about simulating the whole embryology etc so that you can tell what someone looked like starting from their genome.

I've been taking the position that a simulation capable of doing that is unlikely because DNA does not work like that - it is not so much a blue-print as a recipe ... and that is probably going a tad far.

However, I am hard pressed to support this idea, and the state of knowledge has certainly changed since I last looked at this (early 90's - where it was generally considered doubtful that you could sequence fossil, or just very old, DNA.)

Identical human DNA does lead to identical twins ... but they tend to share a womb as well. Would the genetically identical fetuses develop identically in different wombs?

How different can genetically identical twins get?
 
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  • #2
Simon Bridge said:
Identical human DNA does lead to identical twins

Does it?

I don't know, I am sincerely asking. But somehow I doubt they are perfect copies even at birth.
 
  • #3
An interesting question would be how epigenetically identical monozygotic twins are.
 
  • #4
@Borek:
I have known three sets of identical twins ... two sets were very very identical and one were just uncannily identical. But they all grew up together. One of the "seriously you cannot tell them apart" pair hated being identical and took pains to look different and it was still hard. It was only resolved when one got caught in a barbed wire fence and ended up with one of those scars over the eye.

I got to be able to tell them apart by their body-language ... which would take a while.
Seriously, their own parents couldn't tell.

However - via skeptics networks, I have heard that identical twins need not be all that identical. There is a tendency to learn to be identical as kids, and studies have tended to select for very alike twins for subjects.

@Ryan - thanks for the terminology :) that reminds me:

I am (JIC there's a pedant reading this) not including differences obtained through misadventure or surgery.

In a way what I am really asking is "to what extent does your genome determine your appearance?" But I'm trying to be clever. I was hoping that some fertility clinic has implanted identical kids in different mothers and kept track. I doubt we'd get a deliberate experiment of this kind past the ethics committee.
 

1. How do genetically identical twins differ?

Genetically identical twins, also known as monozygotic twins, come from a single fertilized egg that splits into two embryos. They have nearly identical DNA, but can differ in subtle ways due to environmental factors and random mutations. This can lead to differences in physical characteristics, personality traits, and susceptibility to diseases.

2. Can genetically identical twins have different fingerprints?

Yes, while identical twins share the same DNA, their fingerprints are formed in the womb and can be influenced by factors such as the position of the fetus, the amount of amniotic fluid, and the pressure exerted by the uterine wall. Therefore, identical twins can have slight variations in their fingerprints.

3. Do genetically identical twins have the same personality?

No, even though genetically identical twins share the same DNA, their personalities can differ due to environmental factors and individual experiences. While they may have similar interests and preferences, they can have different temperaments, attitudes, and behaviors.

4. Can genetically identical twins have different medical conditions?

Yes, while identical twins have a higher chance of sharing the same medical conditions due to their genetic makeup, they can still develop different diseases. This can be due to environmental factors, lifestyle choices, and random mutations that can occur in one twin's DNA but not the other's.

5. How do researchers study the differences between genetically identical twins?

Researchers often use identical twins in studies to understand the impact of genetic and environmental influences on certain traits. They can compare the similarities and differences between twins raised in the same environment and those raised in different environments. This helps to identify the role of genetics in shaping an individual's characteristics.

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