Wednesday, December 4, 2013

We May Inherit Our Fears

ImageIt can be hard to figure out where our fears and anxieties come from, but perhaps we should look to our own history for answers. A new study published in Nature Neuroscience suggests that your fears could be passed on to your children and your children’s children, a finding surprising enough to stir up some controversy. The study proposes that this occurs through something called transgenerational epigenetic inheritance.

So what exactly is transgenerational epigenetic inheritance? According to Nature Reviews Genetics, it can be defined as “effects on a phenotype (or on patterns of gene expression) that are passed from one generation to the next by molecules in the germ cells and that cannot be explained by Mendelian genetics (or by changes to the primary DNA sequence).” Or in simpler words, epigenetic modifications “alter the expression of genes, but not their actual nucleotide sequence.”

How does this apply to fears? Researchers Brian Dias and Kerry Ressler of Emory University demonstrated the supposed inheritability of fear by conditioning male mice to fear a certain smell, that of a chemical called acetophenone. Ten days after conditioning, these mice, the F0 generation, were allowed to mate. Their babies, the F1 generation, showed sensitivity to the odor of acetophenone, a scent they had previously not experienced. When the F2 generation came along, they showed a similar sensitivity.

What is crucial here is that the environmental conditioning took place well before conception and so the original fear induction did not directly affect the F1 offspring as they developed within their mothers.

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