Is the DNA exact the same in twin brothers?

Question

Refered to exact look alike twin brothers

Answer 1

In identical twins -- (from one egg) the DNA is the same.

Answer 2

Yes, in general we can say that identical (homozigotic) twins have the same DNA. However, it may be different because of occasional mutations. Besides that, I think there is another interesting phenomenon concerning B lymphocytes (cells wich produce antibodies). As DNA translates into proteins and it is a finite molecule (antibodies are proteins), it isn't possible for our genome to code for proteins that are specific for any given antigen (and we know that organisms mutate, so antigens are always changing). So apparently DNA in B lymphocytes suffers rearrangement processes so that a virtually infinite number of proteins can be produced. Wich means that, in a single individual, DNA is not exactly the same in all of it's B lymphocytes. I've heard about this but haven't confirmed it. Furthermore, we may still have the interesting cases of chimeras (result from mixture of cells from different zygotes/embryos) and mosaics (result from mutations in one cell line, wich makes those daughter cells genetically different fron the rest of the body cells). In these cases, one individual has genetically different subpopulations of cells. For more information, check Wikipedia. And the question of identical twins fingerprints beeing different is probably just one example to show us how important the interaction with the surrounding medium can be. In fact, studies have proved that the bioquimical environment in the uterus (concentration gradients and interactions of different substances) affect the way embryos develop and is probably one of the factors to explain the differences between identical twins. A for fraternal twins, genetically they are just like any other siblings. Thank you for reminding me of the fingerprint issue. I'm going to post that question myself!

Answer 3

Just answer this questions: How come the identical twinks have different fingerprints if their DNA is identical? Impossible. The DNA is unique for every single person. OK, the DNA would be very similar, but not identical.

Answer 4

Yes! The zygote splits into two at a very very early stage. Because there was only one egg and sperm involved, the zygote only had one version of DNA. Therefore, when it splits, the two "daughter" zygotes will also have the same DNA coding. The two zygotes now share the same placenta and have the same coding.

In non-lookalikes, there are seperate DNA codings- because there were two eggs and two seperate sperm.

Hope this helps.

Answer 5

the only way to be completely sure is to fully sequence both - I would think there are some changes that occur after separation - I have identical twin cousins that are adults now and they are not the same height - that cant be from an outside influence, nature vs nurture, that has to be a genetic difference

Answer 6

Only identical twins have the same DNA, and ferternal twins have very similar DNA, but because they don't look the same, their DNA is different.

Answer 7

yes, the dna in twin brothers cannot be distinguished from. If you were to have intercourse with twin brothers and got pregnant you would not be able to tell who the father was.

Answer 8

I know everyone here being a genius and all, SHOULD know enough not to think DNA can be identical. Even if cloned there will be, although very slight, a few very subtle differences in the DNA patterns. Like snow flakes...just because they MAY look alike doesn't make it so....sorry to bust your bubble.

Answer 9

In identical twins, yes.

Answer 10

nope. no one has the same finger- and foot-print, right? those kind of details are stored in the DNA. identical twins are a close match, though.