How the Wiring of Your Brain Shapes Who You Are

Reviewing the book ‘Innate’ by Kevin J. Mitchell

I wanted to get a deeper dive into genetics, but I didn’t want to deal with genetics on a level that was too abstract. Given that I’m very keen on psychology, the genetics of psychological traits tend to interest me the most. So when I saw this book it looked like the perfect opportunity.

The book is written by Kevin Mitchell, a very successful neuroscientist, and it explores what causes human diversity and individual differences. How genetic processes end up writing our brains differently, and how that ends up in different traits such as a personality, intelligence, sexuality, and so forth.

The broad point is that psychological and behavioral traits are heavily genetic. Depending on the trait, it can be anywhere from 30% to 80%. This largely comes from studies dealing with twins (monozygotic twins vs dizygotic twins and monozygotic twins reared apart). The author doesn’t spend too much time on this point, and rightfully so. Despite the controversy, it is a rather basic and accepted fact, and the book is focused on exploring why this is the case rather than arguing it to death as some have done.

The first part of the book was a very general introduction. Not only to genetics but because we are dealing with how the brain is wired, the brain itself. This alone is well worth the book, and it was a fantastic introduction to cognitive and neuroscience. The second part goes into more specific areas of innate differences and their mechanisms.

The book is somewhat similar to Pinker’s Blank Slate, but I liked this one better. It is much heavier on science, and it doesn’t go so much on philosophy or politics. I hate when these topics are full of apologetics and endless cautionary statements. I understand why they are required, but I feel like they detract from science, which should be the main point. I found the author balances this perfectly. It only dives into politics and controversies when absolutely required and keeps it very succinct and brief. The rest is science.

Something else that I liked is that the book had a wide range of topics, some politically controversial (like IQ or sex differences), and some very benign (like personality traits). But they were dealt, for the most part, the same. As I think they should. It wasn’t trying to avoid controversy by skipping hot topics, but likewise, it wasn’t focusing on them to make the book controversial or aggressive.

Something that really stuck with me was how much randomness there is for genetic mutations. There is often a debate between nature and nurture. That is often a false dichotomy, but beyond that, it is missing an important variable entirely: chance. When studies often find a high contribution from genetics, it seems to assume that the leftover is the environment. But often, it is not the case because that’s measured with the shared environment of twins. Some of the variation is completely random from the neurodevelopmental process of the brain. Random fluctuations in cellular components are unavoidable noise that accumulates and ends up affecting how the brain is wired. Meaning that a trait can be only partly genetic but still entirely innate with little influence from the environment.

I really liked the author’s emphasis on how genetics also shape the environment, making the dichotomy even more problematic. If one is musically talented, they are more likely to pursue musical training. The training isn’t genetic, it is part of the environment. Yet, that environment was chosen based on a genetic influence. Viewing it as a purely environmental factor is misleading.

Another example given that I liked is how a child with autism may have less interest in people’s eyes. This will lead to missing social cues that will shape the development of language and communication. Where do these social deficits come from? They weren’t purely genetic, but they certainly can’t be attributed to the environment alone either.

Furthermore, genetics isn’t simply how you’re born. It is a developmental process which includes maturation. Much like physical attributes, the genetics of brain wiring is a long process that isn’t exclusive to neither gestation nor even childhood.

While this wasn’t a big point in the book at all, the author articulated something I have been thinking about for a good while about group differences. Stereotypes often have a grain of truth. While for example differences between men and women are certainly amplified and distorted by our culture, there are differences nevertheless. The stereotypes seem to coincide (they aren’t completely random), but very often in an exaggerated manner. They end up this way because they are oversimplified yet effective heuristics to make predictions with little information. But they end up very off when applied to specific individuals. Trying to claim the stereotypes are completely inaccurate is not helpful because it is untrue. Yet, adhering to such stereotypes is also counter-productive as they most certainly distort reality with oversimplified schemas. The goal should be to clarify why the stereotypes are oversimplifications and also to judge individuals by themselves without group labels.

Overall it’s a very solid book. If you’re interested in psychological traits or genetics, I think anyone would really enjoy it and finish it with a much better understanding of the underlying science. If you are interested in both, then I doubt there is a book better done than this.

There is often a trade-off in many of these types of books. Not describing the science enough vs being too technical, or getting too dragged into political controversy vs not preventing unfair criticism and misinterpretation. I think Mitchell nailed these trade-offs perfectly and wrote a deeply educational and enjoyable book about a fascinating topic.

If you’re new to neuroscience or genetics, I would recommend getting the paperback and not the audiobook. While I chose the latter, many of the topics I was already familiar with. If I wasn’t, I think the beginning of the book, which gives the required technical background, would be difficult to follow. If you’re new, it’s worth having the opportunity to read it instead of listening so you can take your time and have better retention.

Thanks for reading! If you like non-fiction book reviews, feel free to follow me on Medium. If you don’t use Medium, you can sign up for email notifications of my posts or subscribe to my Substack.