• Question: Do identical twins have identical DNA?

    Asked by nettyra to Daz, Cat on 24 Jun 2011.
    • Photo: Cat O'Connor

      Cat O'Connor answered on 24 Jun 2011:

      Heya Nettyra,

      So it turns out that this question is a little bit harder than I originally thought!

      It was always believed that identical twins had identical DNA because identical twins are formed when one fertilised egg splits into two. But since we now have some pretty nifty machines to test really complicate parts of DNA, they’ve found that identical twins are in fact a tiny bit different genetically!

      But even though they may be nearly genetically identical, twins can be phenotypically different! What this means is that while they are both made of the same DNA, that the way the DNA is expressed may be different, so that they can have different outwards appearance!

      The finding that identical twins are not genetically identical is obviously very good news for forensic scientists. This means that if one twin commits a crime, they can find out which one did it!!

      I’ve found this nice news story that talks about this research a bit that you may like to read: http://www.nytimes.com/2008/03/11/health/11real.html

      Hope this helps,

      Cat 😀