Any biologists on NSC?

[Gwylan]

We're having a quick debate at work. Do identical twins have identical DNA? And if so, do non-identical twins?

We reckon identical twins do but aren't so sure about other twins.

 

[Easy 10]

I'm no biologist, but I have seen Jurassic Park.
Surely nobody can have identical DNA, not even twins.

 

[Barnet Seagull]

Identical twins have identical dna.

 

[Barnet Seagull]

It's only one fertilised egg which is split so they must have the same genetic makeup.

 

[perseus]

Same DNA (most likely) but different fingerprints.

 

[Lush]

I will ask my other half when he gets home. He is a patent lawyer specialising in human genetics.

 

[London Irish]

Surely people with identical DNA are clones, of the non-disco dancing variety.

 

[beorhthelm]

hmm, Barnet makes a good case, but...

If the finger prints are different, then the DNA must be too? Also changes can occur to DNA after the egg splits.

So i reckon no.

 

[US Seagull]

Identical twins have identical DNA. As barnet said, they split from the same egg. Non-identical twins do not have the same DNA. Fingerprints have absolutely nothing to do with it since they are influenced by environmental factors.
Clones are no different that identical twins except for the possibility that you could have a clone that is many years younger than you.

 

[Lush]

Exactly. My other half says...

"Identical twins have identical DNA. They are created when a fertilised egg, on its first division, forms two identical daughter cells which then each go on to form an embryo. A natural form of human cloning, perhaps?

However in saying this I have not taken into account minor mutations in DNA that may take place during normal development from the original cell to the fully formed adult.

Non-identical twins are like normal siblings, only born at more or less the same time instead of 2 years apart (or whatever)."

 

[Gwylan]

What mine of erudition NSC is, there's always someone who can give a sensible answer.

Next week, an explanation of the Big Bang theory...

 

[maffew]

do they really have identical DNA? so if one of them commited a crime and they did a DNA test neither could be proved guilty? Or you could have children and not be able to prove which one was the father/mother?

 

[Hungry Joe.]

I work with a girl called Blanche who has an imaginary identical twin. They're both half French.

 

[Meade's Ball]

I will ask my other half when he gets home.

Are you a Siamese twin?

 

[US Seagull]

do they really have identical DNA?

Yes.

so if one of them commited a crime and they did a DNA test neither could be proved guilty?

Yes. DNA would prove that one of them did it, but not which one. You'd need some extra evidence.

Or you could have children and not be able to prove which one was the father/mother?

Yes. Again, you could prove that one of them did, but not which one.
All good questions BTW.

 

[lincs seagull]

I thought identical dna was a clone

But i thought that identical twins share 99% dna.

some thing i saw on the discovery channel

not sure

 

[Pevenseagull]

There appears to be a lack to familiarity with/ acceptance of transposons, identical twins cannot have identical DNA.

should Branston Pickle be kept in the fridge?

 

[London Irish]

Here's another view that backs up Mr Lush and US Seagull's view that they are natural clones.

http://www.straightdope.com/mailbag/mtwinsdna.html

Would they have the same fingerprints, though? A less clear answer, similar but different. http://www.straightdope.com/classics/a980821.html

I too find Maffew's scenarios intriguing. Given the amount of crime dramas pumped out by TV, what a hell of a plot line not to have been covered - evil twin commits murder and assorted fiendish acts, leaves DNA behind, and dumb rozzers pick up pillar-of-the-community twin, much to the angiush of all concerned. If only there was some pulp writers among us who could make a bit of money selling the script.

 

[Gwylan]

The same thought had struck me, LI, I think the problem with it is that it would be too obvious. Afficionados of detective stories would work out very quickly that the other twin would have done it (although it might work out better if the 'good' twin committed the murders on the grounds that the 'evil' twin got the blame).

A better plot would be for the other identical twin to be unknown, maybe the mother gave him away at birth as she couldn't bring two children up and he has led a life away from the main action. So, she went to Leeds, say, to give birth, gave away the twin to brought up locally, went back to London with the remaining child, who grew up to be a successful property developer. But then, his DNA is found on a murder victim in Leeds.....


Any thriller writers on NSC?

 

[beorhthelm]

actually, i think there was a film with a plot along those lines.

Probably very crap since we cant remember it.