• Question: are my genes unique?

    Asked by hollstar to Anouk, Chris, Judith, Leisha, Seyyed on 15 Jun 2012.
    • Photo: Chris Kettle

      Chris Kettle answered on 15 Jun 2012:

      Hollstar – Yes and No.

      Your genes themselves are shared between all humans and some animals.The genetic information of YOUR genes may differ from other humans by changes to the DNA code, when these have no effect they are called polymorphisms.

      You may have some genes that other humans don’t have and they may have genes that you don’t. Essential genes will always be present and when missing tend to show up as some kind of disability or “abnormality”.

      You are unique (even if you are an identical twin as the environment will act on the same DNA differently) mainly due to the combination of the sub-type of genes you have, but your genes are not.

    • Photo: Judith Sleeman

      Judith Sleeman answered on 15 Jun 2012:

      Yes, indeed your genes are unique! As Chris says, we all have the same basic set of genes (otherwise the human genome project would have been a huge waste of time and money!) but each gene can have different versions or ‘alleles’. You inherited on allele for each gene from each of your parents and the combination you have is unique.

      A straightforward(ish) example is the ABO blood group. There are three alleles A, B and O. A and B are both dominant alleles, while O is recessive. If your parents had the alleles AO and BO, one parent would have the blood group A (because the O is recessive) and the other would have the blood group B. However, you could have any combination of the alleles: AO (blood group A), OB (blood group B), AB (blood group AB) or OO (blood group O).

      As well as getting a different assortment of alleles of all of the different genes, there will also be differences in how much each gene is used in different cells. This can result from all sorts of things including diet, illnesses, the environment. This is the basis of a whole field of science called ‘epigenetics’ and helps to explain why identical twins, who start off with exactly the same set of genes, are actually far from identical.

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