Tuesday, September 8, 2015

Is trauma in our genes? Ethical implications of epigenetic findings

by Neil Levy

Neil Levy is professor of philosophy at Macquarie University, Sydney and deputy director of the Oxford Centre for Neuroethics. He is the author of 7 books, including Neuroethics (2007) and Consciousness and Moral Responsibility (2014), and edits the journal Neuroethics. He is also a member of the AJOB Neuroscience board.

A recent study by Rachel Yehuda et al. in Biological Psychiatry provided further evidence for the genetic transmission of acquired characteristics, by showing that Holocaust survivors passed certain acquired genetic markers to their children. The idea that acquired characteristics can be genetically transmitted is (roughly) equivalent to the doctrine of Lamarckism, and was long considered a heresy in biology. [Editor's note: see also Ryan Purcell's 2014 post for this blog on the relationship between Lamarckism and epigenetics.] According to the Darwinian orthodoxy, traits change because randomly occurring mutations confer a relative fitness advantage on some organisms, not because they change their behaviour, and that change then comes to be encoded in the genes. But the orthodoxy has long been shattered. Scientists now recognize that the story is a lot more complex than that.

This new study is of central interest to neuroethics for many reasons. One is that the trait in question is psychological, or at least very plausibly underlies a disposition to certain psychological responses, given the right circumstances. Children of Holocaust survivors are themselves at higher risk for stress disorders: a propensity to stress disorders is inherited. How does the inheritance work? One possibility is that their parents behave differently, due to the trauma they experienced, and this difference in how they treat their children causes the difference in susceptibility. Another possibility is that the trauma caused an alteration in the genes of the parents, and this alteration was then transmitted biologically – in the DNA or cytoplasm – to children. Of course, these are not exclusive possibilities – its very likely that people who have been massively traumatized have persisting psychological problems that affect their parenting. The new study strongly suggests that in addition to any such transmission of a vulnerability to stress disorders, there is also biological transmission. In effect, the children of Holocaust survivors were born with bodies “prepared” for stress. What might have been (somewhat) protective, had their world been as massively awful as their parents’, proved instead to be maladaptive.

Buchenwald concentration camp, WWII

Studies like this show that many of the subdisciplinary boundaries we are wont to draw – bioethics or even genethics versus neuroethics, for instance – do not mark boundaries that nature respects. While it is a mistake, I think, to identify the mind with the brain, the mind is nevertheless dependent on and realized by entirely physical properties: it falls within the province of those studying the body and how it is constructed. Equally, bioethics doesn’t have an exclusive right to the somatic: in order to understand the mind, we need to be able to understand the somatic too.

The study has an upshot, too, for one of the most cherished distinctions in genethics: between ‘germline’ and ‘somatic’ interventions. Many bioethicists think it is permissible for adults to make changes in themselves so long as they limit those changes to cells that will not be transmitted to future generations. But epigenetic effects, which are only just beginning to be understood, make this distinction extremely hard to draw. In fact, interventions may be transmissible in indirect and unsuspected ways: people may change their environment, which changes their cells in ways that are then transmitted. The very idea that germline interventions are more problematic may be a product of a mistaken view about genes as especially powerful and uniquely segregated units of reproduction. In fact, we transmit all kinds of things to future generations, by all kinds of causal routes, from shared culture to built environment to ideas to DNA and other cellular resources. All these factors are inextricably intertwined and none are causally privileged as the dominant cause of the resulting people.

Want to cite this post?

Levy, N. (2015). Is trauma in our genes? Ethical implications of epigenetic findings. The Neuroethics Blog. Retrieved on Retrieved on , from http://www.theneuroethicsblog.com/2015/09/is-trauma-in-our-genes-ethical.html

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