The choice to undertake a longer education is generally seen as just that – a choice – assuming you are able to afford it, of course. However, it may come as a surprise to you that there is a grouping of genetic markers that, if contained within your genome, predisposition you towards staying in education a little longer than others.

Remarkably, this isn’t a new piece of information. What is new, sadly, is that this gene group may be becoming less common over time.

As reported in the Proceedings of the National Academy of Sciences, between 1910 and 1975 in Iceland, these pro-education genetic variants appeared increasingly less across this time period. It appears that they are undergoing negative selection, although why is currently unclear.

First off, it may seem unusual that Iceland was the focus of this study, but there’s a reason for this. Iceland’s population is less than most major European cities – 331,778 as of 2016 – and they all share a very common ancestry. Whereas much of Europe was populated tens of millennia ago by our species, Iceland’s land of fire and ice was settled much later, around the year 800, by Scandinavians.

Since then, they have been a rather isolated people, which means there is little genetic variation in the population. That means that small changes to their genes are easily tracked, with causes more easily attributed, than most other countries on Earth.

deCODE, a genetics firm in Reykjavik, has benefitted greatly from researching the genetic evolution of Icelanders, and this new study is no exception.

Importantly, their paper does point out that just having these pro-education genes doesn’t mean you’ll automatically end up with a master’s degree or a doctorate. In fact, plenty of people with these genes lived a life that was quite the opposite.

Nevertheless, this genetic group does correlate with a tendency to stay in education longer, so its decline over time is a tad worrying.

It must be noted, though, that the effect is fairly small – it matches up to a drop in IQ of around 0.04 to 0.3 points per decade. Still, if this trend continues, it’s clearly not a good sign with regards to general intelligence.

“The cumulative effect over time means this is going to have a dramatic effect on the genetic predisposition to educational attainment,” coordinating researcher Kári Stefánsson, a professor of neuroscience and founder of deCODE, told the Guardian. “Unless something comes along to counteract that, it could have a profound effect on educational attainment in our society.”