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Can mutations be inherited by children? References wanted

  1. Aug 29, 2013 #1

    Consider person A. She has a (genetic) mutation in trait T. By comparing to her parents, we conclude that T was not inherited from parents since they lack T.

    Now A marry another person B. He has a moderate "amount" of T.

    They give birth to a child C. I know that there are probabilities going on here, but my point is, when we consider A as mother and C as child, can we say anything about the heritability of T from A to C?

    If T should be specified, consider it the intelligence (Yes, I DO know that there is much of debate about how much of intelegance is due to parents and how much is due to environment, etc. But this is not the point here)
    Last edited: Aug 29, 2013
  2. jcsd
  3. Aug 29, 2013 #2


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    The word is 'intelligence'. It looks really bad when you misspell it.

    Yes, mutations can be passed on to offspring. A rather famous mutation in humans is the gene which allows for the production of lactase in adults.


    Before this mutation developed, adults could not digest milk or milk products. After the mutation developed, particularly in Europe, cheese making and Cheeseheads rapidly increased, allowing for the use of a particularly nutritious foodstuff which could be stored when not needed.

    In parts of Asia, large numbers of people do not have this mutation and thus are not able to digest milk or cheese.
  4. Aug 29, 2013 #3
    Thanks. Can you refer me to a good book about this topic, i.e. the heritability of triats, something that a physicist (w/o much biology background) can understand...
  5. Aug 30, 2013 #4


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    Not really. It's not a field I'm familiar with in detail. You could try googling 'genetics' or 'mutation' and see what references pop up.
  6. Aug 30, 2013 #5


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    First a clarification. Traits do not mutate; genes mutate. Sometimes mutations to genes can create alleles (gene variants) that directly cause a particular trait, but often the picture is very complicated. One traits is often controlled by the combined effect of many genes. Furthermore, one gene often affects the expression of many traits. To simplify the discussion, we'll consider only traits that are caused primarily to mutations in one gene (e.g. the trait cystic fibrosis, a disease caused by mutation in the CTFR gene).

    First, if a child has trait T but the parents lack trait T, this does not necessarily imply that the trait is due to a new mutation. Many traits are recessive, meaning that they are expressed only when an individual contains two copies of the associated allele (remember that we have two copies of each gene in our bodies: one copy we inherit from our mother and one copy we inherit from our father). This is the case with cystic fibrosis. So consider the case of two parents, each of whom have one functional allele of the CTFR gene and one disease-causing allele. These two individuals will not have cystic fibrosis because each has a functional copy of the CTFR gene. However, if they both pass on their disease-causing allele to their child, the child will have no functional copies of the CTFR gene and will therefore develop cystic fibrosis.

    That said, there are many cases where an individual shows a particular trait, caused by a specific mutation and that mutations is not present in either of that individuals parents. We call these types of mutations de novo mutations (just a fancy way of saying new mutations). Whether such individuals can pass on their de novo mutations to their offspring depends on whether these mutations are present in their germ cells (egg or sperm cells).

    Sometimes such de novo mutations arise in adulthood in a particular tissue. This is the case for many cancer-causing mutations. Here, the mutation is present only in a few cells of the individual's body (e.g. at the site of the cancer), so it will not be present in the germ cells, and therefore it cannot be passed to the individual's offspring. Some de novo mutations do not arise in that individual, however, but instead arose in the sperm or egg cell of that individual's parents. In this case, such a mutation would be present in every cell of that individual's body, including the germ cells, so the mutation could be passed to the individual's offspring.
  7. Aug 31, 2013 #6
    That was comprehensive, thank you!

    So, it is complicated...

    Thanks again for your time.
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