In her new book, the scientist examines the role of fate in our lives, how our politics are formed and sniffing out Mr Right

Dr Hannah Critchlow is a neuroscientist at the University of Cambridge. Her debut book, The Science of Fate, examines how much of our life is predetermined at birth and to what extent we are in control of our destiny.

How has the slow march of scientific research affected our concept of fate? On one hand, we know more about how genetics drives our lives, yet we also have more good evidence for things that we can do to shape our own outcomes.

This concept of fate and destiny has around since the Greeks – it threads through different cultures and is deeply rooted in the way that we speak today; for instance, we often say that babies are born destined for greatness.

It’s a seductive idea. If outcomes are predetermined, that absolves us of blame when things go wrong.

Yeah, in some ways it’s a really nice idea, it’s a get-out-of-jail card: we are who we are, so we can just rest on our laurels. It’s quite reassuring. As a parent, I find it quite comforting for my child, because there are a millions of decisions that I have to make for him and it’s quite nice to think a lot of the work has been done now. The genes, the basic neural circuitry that acts as foundation for his life is already there.

If you ask long-term couples to think about their partner, their brain will react in the same way as a drug addict’s

But as your book explains, our brains are quite plastic…

In 2000, a landmark study demonstrated how the brains of London black-cab drivers changed as they took the Knowledge. The hippocampus, which is involved in navigation, learning and memory, enlarged in cabbies who passed the test. This study got a lot of attention and informed the idea that we can hone our brains in the same way as muscle and therefore change our ingrained habits, even become superhumans if we just train our brains in the right way. But now there’s a lot of information coming out of the genomics revolution, particularly studying how neural circuits are laid down under the direction of DNA in babies at just 20 weeks’ gestation and we’re seeing a lot of behaviours are ingrained or coded from very early on. For example, anxiety, obesity, depression and addictive behaviour have all been revealed to have a quite high hereditary basis. But of course, all these behaviours may be amplified and reinforced by the decisions of our parents.

The concept of fate is often used in the context of love and choosing a partner. In your book, you talk about a study that give a scientific explanation for the idea that “opposites attract”.

A panel of men was asked to wear a T-shirt for several nights and days and they weren’t allowed to wear deodorant or eat anything too smelly. The T-shirts were presented to an array of women who were asked to sniff then and rate them in terms of attractiveness based purely on smell. It turns out that the females rated the males as more attractive if their MHC [major histocompatibility complex] systems were different from their own, because then their offspring would have a stronger immune system, a better range of armoury against potential infections. So women were kind of sniffing out Mr Right.

What else does neuroscience tell us about a successful relationship?

If you image the brains of the couples who have been together for a long, long time and ask them to think about their partner, their brain will react in the same way as a drug addict’s. You can almost say this couple are addicted to each other.

You say “affection is a neurochemical event” – that’s not very romantic.

Valentine’s Day with me is a lot of fun!

You devote a chapter to the formation of belief – how our genes, traits and experiences shape our views. Does this mean genes play a role in our political views, say whether we’re a leaver or a remainer?

There have definitely been studies that have looked at different brain profiles associated with ideology. People who are very conservative seem to have a much larger volume and a much more sensitive amygdala – the area of the brain that is involved in perceptions of fear. People who are more liberal seem to have a greater weighting on the region of the brain that is engaged in future planning and more collaborative partnerships. They don’t seem sensitive to immediate threats; instead, they are looking to the future. What we see in propaganda through the centuries is that if you heighten someone’s fear response using environmental manipulation, you are more likely to make them vote in a rightwing way.

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So what does neuroscience tell us about how you might go about changing someone’s mind or winning an argument?

It’s very difficult. Once you have built up a perception of the world, you will ignore any information to the contrary. Your brain is already taking up about 20% of your energy, so changing the way that you think is going to be quite cognitively costly. And it might be quite socially costly too.

Are you concerned that the more we know about how DNA determines outcomes, there will be increasing interest in screening embryos and gene-editing, with the aim of avoiding traits which are deemed undesirable or increasing the probability of traits which are thought advantageous?

There has been a huge growth in technologies that are allowing us to understand the brain, understand what gives rise to our complex behaviours, coupled with technologies that allow us to sequence our DNA and then edit our DNA, and also changes in IVF techniques and practices. It’s very timely we have this discussion about destiny and fate and where we want to go as a species. Some companies are going to start commercialising this even though the science isn’t quite there yet.

As we learn more about how our brains give rise to the staggering breadth of different behaviours, we see how each of us has a unique cartography of the mind, like a roadway that maps our choices and our strengths. The more we can appreciate that we are each different and that actually that’s a good thing for the species as a whole, we should understand that this neurodiversity shouldn’t be wiped out.

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The subtitle of your book is “Why your future is more predictable than you think”; ultimately, you argue that there is no such thing as free will?

We are just processing information within a cartography of our mind that gives rise mechanistically to our behaviour. So the decisions that we think we are consciously deciding on and making, actually it’s all just an illusion that can be reduced to what our brain is telling us to do.

• The Science of Fate: Why Your Future is More Predictable Than You Think by Hannah Critchlow is published by Hodder & Stoughton (£20). To order a copy go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99