Think of someone whose political ideology leads them to ignore and groundlessly reject science. Typically, this often describes those on the right of the political spectrum, where climate change, women’s reproductive health, and even evolution are routinely dismissed. But a massive and fast growing field in science—behavioral genetics—has a huge body of conclusive evidence that, at first reading, seems at odds with left-wing ideology.

This week, Robert Plomin, professor of behavioral genetics at King’s College London, published a paper showing that a child’s educational success can be predicted by their genes. Genetic data from 20,000 DNA variants across several genes collectively account for 10% of the differences in children’s educational achievement age 16. At the most extreme ends of this genetic variation is an entire exam grade difference—from A to B grade for those with the highest polygenic score, to B to C grade for those with the lowest.

The notion that success at school could be so influenced by genes is uncomfortable for those who uphold the view that anyone can do or achieve anything they put their mind to. But Plomin’s paper is far from the only publication showing such results. Meta-analysis of 61 twin studies shows that genetic variation accounts for 66% of educational achievement at primary school level.

One set of identical twins raised apart shared many similarities—including flushing the toilet before using it, wearing rubber bands on their wrists, reading magazines from back to front, and dipping their toast in coffee.

And, disquieting though that may be, twin studies have time and again highlighted other aspects of ourselves that seem to be shaped by genes. Nancy Segal, evolutionary psychologist and behavioral geneticist at California State University who has written several books on twin studies, says the research suggests that about 50% of individual differences in personality are affected by genetic variation.

Specific examples of twins who were separated at birth and raised apart show that even our personal quirks have a genetic basis. The two-decade long Minnesota Twin Study, which began in 1983, revealed many such cases—including that of identical twins Oskar and Jack. While Oskar grew up in Nazi Germany as a Catholic who took part in Nazi youth, and Jack grew up Jewish in the Caribbean and spent part of his childhood on an Israeli kibbutz, they shared many similarities—including flushing the toilet before using it, wearing rubber bands on their wrists, reading magazines from back to front, and dipping their toast in coffee.

Segal also mentions the example of twins Jerry and Mark, raised separately, who both grew up to be firemen, and who both enjoy Budweiser and hold their drink of choice with their pinkie finger underneath the can.

“There’s not a gene for doing that sort of thing, but the twin studies force us to consider other explanations,” says Segal. “Could it be that they worry about spilling things, that their hands are made in such a way that they’re more comfortable holding the can that way? Even our quirky habits are not just a matter of random chance but have a real scientific basis in our genetics.”

So we can’t be anything we choose?

Though these scientific findings could be alarming for anyone, the seemingly deterministic perspective seems to contradict the left-wing emphasis on the role of privilege in any person’s success.

There is, after all, no doubt that the environment plays a massive role in our personal achievement. Wealthy children aged 5 with low cognitive abilities are 35% more likely to be high-earners as adults than highly able children from poor families. In the UK, those who went to private school make up just 7% of the population but almost a third of parliament. Money, which often brings access to a stable home, small class sizes, and excellent education, undeniably buys success.

But though the scientific findings in molecular genetics don’t directly contradict this, many who care deeply about the effects of privilege seem to flinch at the research. I’ve spoken to people with no knowledge of the scientific literature but a strong political perspective who insist that such studies about the role of genes simply cannot be true.

Both Segal and Saskia Selzam, lead researcher on Plomin’s paper, say that they’ve experienced the same. “Everyone has their own sets of beliefs. Some people ignore data even when other people are persuaded by it,” says Segal. The evidence is building at such a pace that both say the public seem to have become more accepting over the past couple of years.

“The left-wing view is that everyone’s born the same and you can make everyone achieve the same way. From genetics research, we’ve shown that’s not true.”

But the belief that anyone can be anything they choose—that you could take a child and train them towards literally any goal with success is, says Segal, “such an old-fashioned notion, with absolutely no backing whatsoever.”

After all, she points out, if she wanted to be a world champion sumo wrestler, the chances are “pretty unlikely” given her height and weight. “Genetics sets some realistic limits,” she says.

But Selzam says it’s important not to bury our heads in the sand and ignore the evidence. “The left-wing view is that everyone’s born the same and you can make everyone achieve the same way. From genetics research, we’ve shown that’s not true,” she says. But understanding this can be hugely beneficial for those who are struggling to achieve but don’t know why.

For example, she says there’s been a strong educational emphasis on grit and perseverance—but genetics research shows that this personality trait only predicts 5% of why individuals differ. So over-emphasizing it will have moderately little effect and, in making children feel they’re not trying hard enough, might well make many miserable.

Also, it’s important to note that just because educational achievement is genetically influenced, that doesn’t mean it’s determined by genetics. Selzam gives a comparable example of someone who’s genetically at risk of dyslexia. If that child is treated like everyone else then, chances are, they will go on to develop the disorder. But if you identify that they’re at genetic risk then, through tutoring and one-on-one support, it’s possible to counter that genetic disposition through “environmental engineering.”

The evidence is building

Behavioral genetics is an extremely fast-developing science, the “fastest developing science in human existence,” says Selzam. Human DNA was only decoded 16 years ago, and so researchers have been rushing ahead from that starting point, with rapidly developing technological and methodical advances. Meanwhile, projects with huge sample sizes (Selzam’s own paper relied on research from a study of 293,700 people) allow researchers to find increasingly detailed results.

And though the field may be unnerving, the findings have many practical benefits. Segal suggests that understanding our genetics can help someone with depression find the most suitable therapeutic regime, or explain why an overweight person struggles to lose weight. “You can find explanations for things that help you plan for the future and alter your lifestyle appropriately,” she says.

Selzam says she hopes her work can help create personalized education “so that we acknowledge and understand individual differences and work towards creating equal opportunities for children based on who they are.”

Decoding our genetics can highlight our individual risks and resilience. And, crucially, this research helps us understand ourselves.

“Why do some people go into genetics, why do some people show extraversion, why are some people lethargic?” says Segal. “People are intensely interested in how they come to be who they are.”