When something bad happens to you, is it possible to pass on this psychological trauma to your children?
Can our experiences somehow live on in the next generation?
Should you worry that if your childhood was very difficult, this could somehow affect people further down the family tree, years later?
These are questions that humans have pondered for a long time, and until the discovery of genes (which seemed to indicate inheritance doesn't work like this) there were various theories about how one generation passed things on to the next.
The psychoanalyst Carl Jung came up with the fanciful notion of the collective unconsciousness; that there existed an unconscious mind that was shared by all people and which collected our unconscious thoughts and experiences and put them in a sort of melting pot that influenced our behaviour without us realising it.
When something bad happens to you, is it possible to pass on this psychological trauma to your children? Asks Dr Max Pemberton
Another popular theory was that things that happened to people in life were literally passed on physically down the generations.
The French scientist Lamarck used the giraffe as an example and concluded that as it stretched its neck to reach the top leaves on a tree, the neck got longer — and this longer neck was passed on to future generation.
Obviously this isn't true, or things such as scars would also be passed on.
But the advent of genetic science put all these theories to rest. We finally understood that we inherited sets of genetic information from our parents, and that these were fixed.
Our genetic make up didn't change depending on what happened to us during our lives but was set at birth.
However, we've now realised this also isn't true.
The birth of epigenetics — the study of how our environment affects genes and the way they are expressed — has produced some startling revelations.
This week, a fascinating piece of research was published which flew in the face of much of the basic understanding of genetic inheritance.
The psychoanalyst Carl Jung (pictured) came up with the fanciful notion of the collective unconsciousness; that there existed an unconscious mind that was shared by all people and which collected our unconscious thoughts and experiences and put them in a sort of melting pot that influenced our behaviour without us realising it
It showed that childhood trauma can be passed on from one generation to the next — and that this can have serious implications for the mental health of the family's future generations.
So those early ideas weren't so fanciful after all. The study looked at the offspring of children displaced due to World War II, and showed that childhood trauma altered genes that could then be passed on to future generations.
These altered genes made people more susceptible to mental health problems such as depression.
The study found the next generation was four times more likely to experience mental health problems.
Not only does this show how immensely complex genetics are (we clearly have only the faintest grasp of them), but this research has tremendous implications for both society and individuals.
Poverty and inequality does not just affect this generation, it jeopardises the mental health of the next — and we're storing up trouble for ourselves unless we do more to improve the living standards of poor children.
The French scientist Lamarck (pictured) used the giraffe as an example and concluded that as it stretched its neck to reach the top leaves on a tree, the neck got longer — and this longer neck was passed on to future generation
I also think it gives weight to the need to step in early and remove children from abusive families.
But it has implications for many other people, too. If you've had a difficult upbringing, for instance, is that it? Are your progeny condemned to inherit this?
This is where I think things are very interesting. There's some evidence that addressing the trauma helps to nullify the effect it has on genes.
Tackling the problems that you've had in your life —– by having psychotherapy, for example, to process and understand the trauma and allow yourself to move on from this — can reverse the risk that your genes will be altered and passed on.
It also emphasises the importance of early mental health input if youngsters are having a difficult time.
So if you're concerned about your child or grandchild, don't assume things will blow over: get professional help.
This science is still in its infancy, but it does suggest the 'stiff upper lip' mentality and trying to ignore our difficulties can