The Irish Medical Times - Generational trauma: can trauma leave a genetic impact on descedants?


Epigenetics doesn’t stop at the metabolism - if you cross a petite Shetland pony and a massive draft horse there can be a difference in appearance of the offspring based on the carrier. If you have a pony carrying the pregnancy the foal will be much smaller than cases where the horse is the surrogate. Through epigenetics the horse activates all the traits in the foetus that would make them most horse-like and vice versa. So, the next time you are in a bar and a horse walks in and the bartender says “Why the long face?”, you can lean over and say “Epigenetics”.  

On the subject of surrogacy, Dr Michael Greger, author of the famous best seller, How Not to Die, believes there is some evidence that an embryo from a slim couple born to an obese surrogate mother could face an increased risk of obesity. 

According to Greger if you look at families where the mother had gastric bypass surgery and examine the children born before the surgery to those born after, (when the mother weighed say 100 lbs lighter), the children born to the lighter version of the Mom had lower rates of inflammation and metabolic derangements, and were three times less at risk of developing severe obesity themselves. He believes this research proves how important it is to prevent the generational legacy of obesity. 

Given a female child is born with all her eggs already in her ovaries, is Greger saying the weight status of a pregnant woman could influence her grandchildrens propensity for obesity? Yes, that’s exactly what he’s saying.

To extrapolate that further, Greger is suggesting that one way to prevent childhood obesity is to avoid adding excess unnecessary weight during pregnancy (this is weight on top of the necessary natural weight gain). Who ever wants to give that speech to a room full of expectant mothers may also want to bear in mind the culture of fat shaming that women are exposed to on a daily basis, their fragile hormonal and mental state, the dissociation and trepidation they may already harbour about their changing body, and the general stress of pregnancy and just being a woman - with all that in mind, knock yourself out with the weight lecture. But maybe don't hang around for a standing ovation. 

That said, the passing down of generational problems should indeed be part of the education around pregnancy. Also the determinants behind obesity including emotional factors should be addressed.

The theory of inheriting metabolic memories from ancestors was studied in the Netherlands as many people have stayed in the same area for generations, therefore providing a good sample of a population that experienced scarcity to abundance. However, there are many examples of communities passing down molecular adaptations - an African slave brought to America starved and traumatized, could have descendants with diabetes today. People born primed to survive starvation are then raised in an environment that is front-loaded with sugar, rendering the epigenetic changes maladaptive. 

Let’s not forget the Irish famine, could that explain to some degree our prevalence of celiac disease, perhaps also our penchant for sweet alcohol, our drift towards depression, and our sardonic slant on life. I also randomly attribute to the famine our ability to talk at great length yet say nothing of consequence (something had to fill the food gap), our inability to form a straight queue (famine walk), and our rugby sporting prowess (the ball is shaped kind of like a potato). 

It’s unclear just how far back a traumatic generational memory might originate. Perhaps a more nebulous example of generational trauma could be a modern day fear of dogs or cats, could this stem from a stone age ancestor who had a rough encounter with a wild animal? If our great granny (x400)  took on a tiger in her youth, are we more likely to flinch when a poodle passes, or are we more likely to wrestle it in a familiar embrace? (Nobody wrestles poodles).   

It’s not just trauma that we can play ‘pass the perpetuating parcel’ with, experiencing love and incorporating that feeling into our physical code can genetically predispose a child to showing love. Of course, the essentials such as food and exercise are impacting how we look as a species. You are what you eat, processed food has changed the shape of humanity, literally. Our faces are smaller and our bodies bigger than our ancestors. But perhaps future humans may become physically smaller as we spend more time on screens and expend less energy. 

If we have a collective traumatic experience with say climate change and move in great numbers to Mars, our survival genes will kick in. Gravity is lower on Mars and the temperature colder, it's possible our limbs would start to lengthen and our body mass increase as the generations adapt. There is also an argument that green skin on Mars would fare better (probably due to the colour of the Martian sun favouring chlorophyll and the composition of the atmosphere on Mars, plus it’s just way cooler). To summarise - our great great great great alien grandchildren are all going to look like the hulk. 

I am intrigued by this idea of memory genetics, people behaving, looking or eating in a certain way not purely because of learned modelled behaviour but due to a physical trait that was picked up along their family tree. 

Living through a trauma could provide an innate resilience for your descendants. I endured a number of cancers before my child was born. Maybe by simply surviving I have provided my daughter with a genetic durability that she will pass down the line. That and a penchant for bad jokes - my dad told me a joke about genetics, my daughter didn’t get it, but I did.