Depending on how old you are and how “up” with science you are, this may be a pretty astounding blog.

Most of you know the “chromosomal theory of inheritance”.  (Bet you didn’t know it’s still a theory!)  It is based upon Mendel’s observations that he made into a law (you know, the dude who studied heredity 170 year ago.).  Mendel was playing with peas and determined how inheritance worked.

Interestingly, the theory was expounded long before we had any idea that that traits were carried on chromosomes.  It was several years before Thomas Hunt Morgan could provide experimental proof.

But, there’s more.  As we live, as we experience life, our DNA collects things and gets changed.  That’s manifested on what we call the epigenome.  It has a slew of compounds and proteins that attach to DNA; these then turn genes on and off.  This process is called marking the genome.

Now, if we are dealing with invertebrates, we have found that the epigenomes are actually inherited by the next generations.  However, mammals pose a more conflicting situation.  That’s because once the sperm fertilizes the egg, there is epigenetic reprogramming.

Why do we care?   Well, our epigenomes carry information about early life stress, diet, exposure to disruptors (think PTSD) , among other environmental factors.  Some research (in mice; Salk Institute for Biological Studies) found that RNA in sperm is involved in epigenetic inheritance.  Others found mice can also inherit information from early life stress.  (Note  The researchers had to use male mice, since they are not involved in nurturing the young, which could be another way these traits manifest.)  The scientists actually found that this inheritance can continue for five generations.

Multiple symptoms- behavioral changes, metabolism, immune system changes, cardiac function all carry to the next generation by epigenome.  Things like risk taking, impaired memory, altered metabolism all get carried.

The research has also found that if the mice are exposed to diverse environment- one that includes social enrichment, exercise, and stimulation after trauma, these inherited symptoms can be reversed.

They researchers also found that if they inject blood from a mouse that has been subject to trauma into a control mouse, it manifests the symptoms of trauma.  This means the blood contains epigenetic cells What they don’t know is what components of the blood are responsible.

The problem is that we can’t test for this in humans.  There are too many other factors (unlike the mice experiments).  It’s also difficult to design an experiment to test these factors.  Which is why, at least for now, we can’t really separate children from their parents.  As such, any data we have is correlational, not causative.

Moreover, our genome has only one code- the epigenetic code has multiple layers.

But, why would we care?  Consider this- do we want our children to inherit PSTD symptoms?  If our epigenome is so encoded (it often is) and the epigenome can be inherited, this could be a result.

We will await further research on this inheritance.

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