Dear P. Ayodeji Idowu

There are two answers !!

Answer 1 -The answer to this question depends on what type of twins they are! There are two types of twins.

In one case, twins can be produced when two eggs are present at the same time inside the mother, and both of these eggs get fertilized. Each of them eventually grows into a separate baby. Because each egg and each sperm started with different DNA, the babies that grow from each have different DNA. These twins are called fraternal twins, and they are just like other siblings, except that they were born at the same time! (This is why sometimes you might meet a brother and sister who say they are twins).

Very, very difficult, it depends on the Coding and noncoding region in gene

https://www.scientificamerican.com/.../identical-twins-genes-are-not-i...

regards

Thanks for this response

You are right, mutations can distinguish twins but epigenetic marks too. See the following links.

mutations differentitating monozygotic twins :

Article Differentiating between monozygotic twins through next gener...

https://www.wired.com/2014/12/genetic-test-distinguishes-identical-twins-may-used-court-first-time/

about epigenetic differences between monozygotic twins :

Article Epigenetics of discordant monozygotic twins: Implications for disease

"Ghost in your genes" explains the answer to your question very well. https://www.youtube.com/watch?v=5gBHtGS0kZM

if we speak of the entire genome and that means the entire genetik information - then in reality no, but of course, philosophically yes...

Thanks Mr Tobias I am asking about similarity in an gene or SNPs. Not entire genome. is it possible to have replica of a GENE in identical twin?

With the understanding that DNA genotyping can be used for crime detection

yes, this is the definition of a twin - possible but my focus is of course that the DNA sequence is only one part of the genome - epigenetics on top etc. etc. so the more parameters you have, the more likely there are differences - by chance "mutations" - therefore the longer the DNA sequence gets you investigate, the bigger the likelihood, that you have a spontaneous mutation etc. and thus this is the reason that twins are in essence not 100.0000000% identical, but for a single gene and only its DNA sequence of say 500bp or even 3000 bp yes, why not?

considering what is now called De Novo mutations it is impossible that two identical twins to have 100% the same DNA.

Dear P. Ayodeji Idowu

There are two answers !!

Answer 1 -The answer to this question depends on what type of twins they are! There are two types of twins.

In one case, twins can be produced when two eggs are present at the same time inside the mother, and both of these eggs get fertilized. Each of them eventually grows into a separate baby. Because each egg and each sperm started with different DNA, the babies that grow from each have different DNA. These twins are called fraternal twins, and they are just like other siblings, except that they were born at the same time! (This is why sometimes you might meet a brother and sister who say they are twins).

In the other situation, there is only one egg, and it is fertilized by only one sperm. Normally the fertilized egg would divide and grow to form one baby. However, sometimes after the egg is fertilized and starts to divide, it can split apart. After it splits apart, each half can continue to divide and grow into a baby! So, in this case, the two babies came from one egg. These kinds of twins are calledidentical twins-- and yes, >b>they do have identical DNA, because they came from the same fertilized egg! You can remember it this way: fraternal twins each have their own DNA, while identical twins share theirs.

Even though identical twins have the exact same DNA, though, they aren't really perfectly identical. That's why every mother can tell her identical twin babies apart. The reason they aren't identical is that each of them develops separately, and lives a separate life. For example, if one of them has an accident riding his bike, then he might injure himself and get a scar, while his twin brother does not have one. Also, some things in development are a little bit random, and not just due to DNA. For example, identical twins have similar, but not identical, fingerprints.

Answer 2:

Identical do have the same genotype. After all, they come from the same fertilized egg. Recent studies have shown that identical twins have very "similar" not "identical" DNA, but for the most part, according to basic biology it is identical. Identical twins aren't completely identical because DNA is essentially like instructions to building something, how your body decides to build that is random.This is why identical twins can have differing fingerprints.Another big factor why identical twins aren't necessarily completely identical is the environment which each of them were raised in. But for the most part, basic biology says identical twins share the same DNA. More research is being done to investigate this.

Dear P. Ayodeji Idowu

Actually, expert opinion might vary - and I’m no expert - but according to what I’ve read, even at conception, identical twins don’t have perfectly identical DNA in many cases. At some point, one of the two twins may end up with additional copies of the gene its twin carries. Through whatever process, an identical twin can also end up losing a gene while the twin keeps it. These are slight differences, but apparently can be big enough - for example - for one twin to have the tendency to get leukemia while the other doesn’t. So, small or not, most people would say such differences are not “trivial,” and a really thorough genetic test can uncover them. As mentioned elsewhere in this thread, mutations can lead to far more differences later in life. One of the items I looked at for this background was a 2008 Scientific American piece titled Identical Twins' Genes Are Not Identical.

After the egg is fertilized by the sperm, it splits into two. This produces two identical embryos, which go on to produce two identical organisms.

Interesting.

Thanks for giving different instances. But under ANY circumstances, is it possible for a twin to replicates a SNPs of DNA probably like 2 or 3 sequences among MANY DNA's that constitute the whole identical twin genome?

If identical twins have the same DNA, how do you tell who the father is?

the father is ... apart from possible SNP markers, see the epigenetic profile but the technic is rather expensive

@ P. Ayodeji,

In general, identical twins should share the same DNA code. They have the same father (this is answered to your later question).

From a genetic point of view, this is possible. But there is still a higher level of variation, its Epigenetics!!

That lead us to understand basics of epigenetic from the ancient knowledge of genetics

Thanks for all contributions