• Question: The same DNA sequence causes different effects, and it all depends on whom you inherit that piece of DNA from is this right?

    Asked by Ayse to Tristan, Sophie, Ravinder, Matt, Barbara on 7 Mar 2015.
    • Photo: Barbara Shih

      Barbara Shih answered on 7 Mar 2015:

      My understanding is that the statement is correct in the 2 scenarios below:

      1) Epigenetics: an example would be the exact same DNA sequence with different level of chemical modifications on sequences within or near the genes. These modifications could make the genes easier or harder to read by the cell’s reading mechanism. http://en.wikipedia.org/wiki/Transgenerational_epigenetics

      2) Copy number variations: you can have multiple copies of a gene/DNA sequence; you might inherit 1 copy from mum and 3 copies from dad. This would cause different effect. Example include obesity (http://www.bionews.org.uk/page_410394.asp)

      I feel like there should be other scenarios, but can’t think of it at the moment. Will update if I thought of anything else.

    • Photo: Matthew Moore

      Matthew Moore answered on 12 Mar 2015:

      It doesn’t typically matter whom your DNA is inherited from. Whether or not a particular gene is from a particular parent shouldn’t matter towards its function.

      Some hypotheses have suggested that chemical modifications to DNA, acquired in ones lifetime (epigenetics) can actually be heritable; some studies even suggest that this might impact on obesity according to the diet of particular ancestors.

      However this is not well substantiated and DNA is not equally inherited further back than your parents. As DNA is recombined in sperm and egg cells, you do in fact get 50% from each parent but not 25% from each grandparent and so on. Diseases such as obesity are incredibly complicated and the genetic susceptibility to them is unclear as the genes associated also have other functions.

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