That genetic information is passed from parents to children is a concept that we have assumed today. However, Does it matter how parents have lived before conceiving their children? We do not talk about the influences within the mother's womb, but that the information of the parents' life is written in the DNA that is passed on to the children before they are conceived. We thought there was no influence until a small town called Överkalix appeared on the map.
Överkalix is a village of farmers near the Swedish border with Finland. It was a hard place to grow up in the 19th century: 70% of families had five or more children, of which 25% had ten or more. There were many mouths to feed given the poor soil they had. The meteorology of the place caused the crops to spoil more or less every five years. History explains it to us Sam Kean in his book The violinist's thumb.
Some periods were absolutely devastating, as in 1830. How do we know all this? Because we have these data reflected in the annals of the town thanks to the priest of the time, who pointed out: "Nothing exceptional to note, although for the eighth consecutive year the crops have spoiled"However, things were not always going wrong, because there were times when there was a great abundance of food. So many, that even families of fifteen members could get fed up. During times of hardship, in the harshest winters, when I could not be reached by dense forests, in the village they cut necks to pigs and cows to endure as they could. It is not a very different story from other isolated villages.
Taking advantage of the detailed information they had, the scientists wanted to know if the food shortage of pregnant mothers could expose their child to long-term health problems. The scientists had reason to believe it, because this same study had been done with about 1,800 children born just or after a famine in the Netherlands due to Nazi occupations and the winter of 1944-1945 when the supply channels froze and ships Freighters could barely arrive. After the release, the diet could be normal again.
The scientists compared each other's lives and saw that in those born under famine there were more cases of schizophrenia, obesity and diabetes. It was conceivable that the famine had altered the chemistry of the uterus that, in turn, could have altered the expression of certain genes. The victims of other modern famines reflected similar results.
But Överkalix offered a new point of view: you could see if those epigenetic effects could persist generations, since they had very detailed birth data along with agricultural data. It made sense to think that there was a link between maternal nutrition and the child's future health, but one thing they discovered and that a priori it didn't make sense is that there was a link between the child's future health and the father's diet. It is clear that the parents did not carry the future child inside, so that link had to travel with the sperm. And even more strange: the child's health improved only if the father had gone hungry. If they had eaten in abundance the children lived less years and suffered more diseases.
The influence was so strong that scientists could also detect it in the father's father, that is, the grandfather. As stated in the aforementioned book:
The men who went hungry ended up marrying and reproducing themselves in different years, so that their children and grandchildren grew up in different decades in Överkalix, some good and others bad; however, everyone benefited as long as the father or grandfather had suffered hardships.
It is clear that we still have much to discover.