We all want to believe the myth of DNA: that it provides an explanation for why we are the way we are. However, it is just not true—genes are never more than just a part of the story.
Actually genes may have a great or small probability of being fortune tellers. As well as no fortune teller can pick the right lotery numbers, whenever gene controlling mechanisms grant only small probabilities for that gene to be expressed, than you depend on luck. Remarkably, there is a probability of the descendent cell to keep the state on/off granted for the parental cell. This is called epigenetics. Some years ago, it was thought that a not so well activated gene would be low expressed in all cells, and that is not true. What happens is that a defective activating mechanism will grant activation in few cells. Add epigenetics to this and you will understand how genes determine greatly or poorly some phenotypes. We depend on luck, if you have a bad gene, still you can be luck that epigenetically it has gotten "on" in the founder cells and the tissue is sord of OK.
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Agustín Fuentes, Ph.D, is a professor in the Department of Anthropology at the University of Notre Dame.
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