Can you inherit the emotional consequences of an ancestor’s horrible experience? Weirdly enough, it’s beginning to look as if the answer might be “yes.”
I am not a biochemist or a neuropsychiatrist nor do I play one on television, so please feel free to check out the article “Trait vs. Fate” in the May 2013 issue of Discover magazine to see if you think I’ve misinterpreted something. It’s certainly possible.
Imagine that when your great-grandmother was a small child she lived through a nightmare. Maybe she was living in a shtetl in the Russian Pale of Settlement or in a family of black sharecroppers in the American South when the local bully boys showed up, killed her father, and raped her mother in front of her.
We are talking about mind-blowing levels of sheer terror that produce stress hormones through the stratosphere. Hold that thought.
Now imagine your DNA as a spiral staircase. Each step is a pair of connected nucleotide bases. Sequences of these pairs of bases are coded instructions that tell cells what proteins to build. Taken as a whole, your DNA is a set of instructions for building you.
There is a growing body of evidence that extreme stress causes instances of a type of molecule called a methyl group to bind themselves here and there along the spiral staircase of your DNA.
When this happens, it impairs the ability of the DNA strand to make copies of the protein being coded for along the stretch of DNA where the methyl group has set up housekeeping. It may not completely shut it down. The stretch of DNA might be something like a four-cylinder engine that’s only hitting on three.
Cells running on the computer code of that DNA—in a brain, for example—may only sorta kinda work. Hold that thought.
Lab rats with heavily methylated DNA in their brain cells do a crappy job of being rats. For one thing, the females are lousy mothers. It’s as if the animals can’t quite get it together.
Studies of suicides, who are almost invariably suffering from chronic, severe depression or crippling anxiety, or both, show very elevated levels of methylated DNA in their brain tissue compared to the brain tissue of people who died of some other cause.
Were some of them born that way?
When DNA replicates, the methyl groups sticking to the DNA strands like molecular ticks get copied as well. This includes the DNA in eggs and sperm. Traumatized rats have shown the ability to pass on the molecular consequences of their traumas. This is almost certainly true of humans as well.
So, yes, you can inherit great-grandma’s emotional trauma, even if you never met her, and it can mess up your life. And you might pass it on to your children.
It is possible that families haunted by generations of mental illness may be passing on methylated DNA created by some tragedy long ago.
Now a piece of good news: scientists can now take rat pups they have put on a track to be impaired adults and inject their brains with a drug called trichostatin A which removes the methyl groups from the pups’ DNA.
The behavioral deficits of the treated animals vanish.