Because many mutations are benign. From an editorial at Nature:
One of the major findings of the Exome Aggregation Consortium (ExAC), the largest-ever catalogue of genetic variation in the protein-coding regions of the human genome, is that many genetic mutations have been misclassified as harmful (M. Lek et al. Nature 536, 285–291; 2016). Authors of that study estimate that each person has lurking in their genome an average of 54 mutations that are currently considered pathogenic — but that about 41 of these occur so frequently in the human population that they aren’t in fact likely to cause severe disease. That finding is having major consequences for some people with such variants, lifting the equivalent of genetic death sentences. More.
This doesn’t sound like good news for genetic fundamentalism.
See also: Researchers: Early life stress shortens telomeres It’s amazing how genetic fundamentalism is falling by the wayside. The genome has got to be the worst thing that ever happened to the Gene, the Selfish Gene, and all that.
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