Innate: How the Wiring of Our Brains Shapes Who We Are

A fascinating addition to the literature on the nature versus nurture debate. Kevin Mitchell’s work argues that genes, the predominant factor in psychological traits, do not merely end at birth. They hugely impact the probabilistic roll of the dice as we develop (the “epigenetic landscape”). Unlike the Mendelian view, where one dominant gene leads to a clear outcome, combinations of genes are blended to make us who we are.At the heart of all this is DNA, the simple, inert coding that has been passed on for millions of years. Mitchell has this analogy that shows its amazing ability: The famously lengthy novel War and Peace has approximately 587,000 words. With an average of five to six letters per word, this amounts to about three million letters. Imagine if you had to copy War and Peace, by hand, letter by letter, but multiply the length by a thousand—that is the scale of the job that a dividing cell has to do when replicating its genome. You’d probably forgive yourself a few errors.Perhaps even more interesting is that DNA has a proofreading repair enzymes that fix most errors that occur.The first part of the book drills home the concepts that psychological traits are mainly effected by 1) a multiplicity of genes acting in concert and 2) variation in how brain circuits develop. Twin studies consistently show little environmental effect on psychological traits. In fact, it is most likely the case that upbringing is effected by genes and not vice versa. A child who is patient and thoughtful, may change the way in which their parents treat them. Even “peak alpha frequency” or the way our brain processes time seems to be “at least 50% heritable.”The second part of the book then goes deep into these concepts. For instance, synesthesia is a condition that melds colors with music tones. It is interesting to hear that musicians such as Billy Joel, Kayne West, Duke Ellington and Pharrell Williams have all had it. Other deep dives:Intelligence:-Flynn effect shows environmental factors at play even though there is high heritability within families.-Adoptive siblings have IQ correlation scores of .25. Biological siblings have a score of .60.-IQ scores taken at age 11 are good predictors of scores at age 87.-Gene variants predict 3% of educational attainment but that could be as high as 30% as we learn more.-High IQ individuals expend less brain activity on difficult tasks since they don’t need to think as hard.-Facial symmetry, a marker of developmental robustness and attractiveness, also correlates to high IQ.-People with very high IQs tend to have relatives with very high IQs.-General intelligence accounts for 40-50% of variation in performance of IQ tests.-Parents and siblings of people with Down syndrome typically have normal IQs because DS is caused by a single, discrete mutation.-Males show greater IQ variance than females: there tend to be a few more intelligent and more low IQ males than females. This may be due to testosterone’s effects on variability, the instability of the X chromosome or perhaps an environment where males are encouraged at an earlier age.-Brain size is associated with higher IQ. Yet, males have a 10% larger brain than females but similar IQs.Gender:-Genders exist because you want DNA diversity so you need both an egg and sperm (at least 2 different organisms, an egg cannot impregnate its own egg).-Since female reproductive ability declines with age, females retain more juvenile features like a high pitched voice.-If one identical twin is homosexual, the other has a 30-50% probability of being homosexual too. For fraternal twins, its 10-20%.-If you cloned a heterosexual male, they would be attracted to women 100% of the time. If you cloned a homosexual, not all clones would be attracted to the same sex.-On the Big 5, women tend to score higher on agreeableness and neuroticism. Slightly better on conscientiousness. Men score higher on openness to new ideas. No strong link to Extraversion.-Developed nations, which have high gender equality, show the greatest degree of difference in personality traits between sexes. Perhaps in wealthy nations, people can expend resources to advertise the resources they have.-Androgen insensitivity syndrome, where testosterone is not detected, could lead to a fetus developing as a women yet having a masculine brain.Autism:-Males show higher rates of autism, ADHD and dyslexia (about a 4:1 ratio), intellectual disability and schizophrenia (about a 3:2 ratio), stuttering (7:3) and Tourette’s syndrome (9:1). Females have a higher prevalence of depression and anxiety disorders, as well as dementia, migraine, and multiple sclerosis (all about a 2:1 ratio).-As rates of autism diagnoses have increased, there has been a matching decrease in rates of diagnosis of “mental retardation” or “intellectual disability”-If one of a pair of identical twins has schizophrenia, the chance that the other will be similarly diagnosed is ~50%. For fraternal twins (of the same sex), this rate is only ~15%. For autism, the rate of identical twins being coaffected is over 80%, while in fraternal twins it is only ~20%.-Environment and heritability are not factors in schizophrenia. It is most likely caused by genetic mutation.-The number of mutations in individuals is linearly related to their fathers’ age when they were conceived. Offspring born to 40-year-old fathers have about twice as many new mutations as those born to 20-year-old fathers.-A child with autism may start out life with less innate interest in other people’s eyes. The child may thus miss out on the social cues of shared gaze that are so important to language development and communication. This may lead to deficits in social cognition or delays in language acquisition, even though language systems were not directly affected by the causal mutation.The author wraps up by talking about two hot button issues today: 1) Neuroplasticity 2) Epigenetics. Neuroplasticity is the idea that the structure of the brain is not fixed. Your brain is constantly being rewired. Epigenetics is the idea that genes can express themselves differently depending on environmental cues. In both cases, Mitchell suggests that while both mechanism allow us to defy genetics in a minute way, we should all be happy with who we are.

This book takes a new look at a very old question, about the nature of who we are as individuals and how we got to be that way, as well as a broader look at why our species has some of the general behavioral qualities it does. An engaging blend of neuroscience and developmental biology, with a fresh perspective on classic twin studies. The author did a great job of threading the needle: the book provides a substantial amount of scientific detail without becoming so dry and dense with information that the reader becomes frustrated or loses interest. This book is in the same class as those by Steven Pinker, Stanislas Dehaene and others directly involved in the science and research, who go well beyond pop-science's superficial treatments but in a way that engages throughout.The only minor flaw: for a few of the major claims or most interesting points made, more footnotes would've helped — less for peace of mind that what's stated is accurate (I have no doubts based on consistency with other scientific works), more for ideas on further reading.Without getting too far into spoiler territory, the author provides compelling evidence that much of what has traditionally been argued as "nurture," is often times more likely to be directed by a person's "nature" or the nature of those around them, then it is to be purely an influence of one's external environment. While the author does not attempt to wholly discredit the idea of nurture and what it can mean, it's pretty clear that we collectively were not looking at this question the right way. Sometimes the way we ask the question or define the terms, guarantees that it will be answered to no one's satisfaction. This book addresses that flaw and in my opinion sheds new light on this old debate, showing why "who we are" is much more a function of nature than nurture.Highly recommended.

The book is very well written and presents the of how the process of development plays a huge role in the our formation, being that the brain or any other structure in our body.Also debunks many misconceptions about nature vs nurture, and shows that in a very didactic way, explaining the research that was done to come to these conclusions, like the twin studies and the fox study.

One of the most illuminating books I've read on the topic of development and individual differences. The author engagingly explains personality, mental illness, and intelligence differences as well as many other topics using the most current and rigorous evidence. The book may upset people who hold strong views on some subjects, but that is usually a good sign in popular science writing. This book deserves being read more than once in order to fully grasp the content.

It has been written that if a person can’t explain a topic with simplicity they don’t really understand it. No issue here. This book very clearly explains the relationship of innate characteristics as genetically stablished framework modified by the complexity of experience laid down on the coded framework. The obvious nature of differences between people, peoples, and genders causes some people a great deal of angst. It shouldn’t. This text helps explain the differences without suggesting determinism or eugenics. There are no claims of value hierarchy, but instead a call to relish and celebrate the variances in the human innate. Quick read.

This is a fascinating and very comprehensive look at how genetics and genetic mutations get expressed in brain development and brain function. The discussion is quite thorough, yet easy to understand from a layman's perspective. The author does an outstanding job of unraveling the complexity of how genetic variations impact neural development, mental health, and cognition, including what rolls these may have played in evolution. I got the book on audio CD which is articulate and easy to understand. Highly recommended for anyone interested in genetics or the mind sciences!

I heard Kevin Mitchell speak at a public lecture on genetics a month or so ago and was captivated by his fascinating research and engaging delivery. Intrigued to learn more, I immediately bought Innate - How the Wiring of Our Brains Shapes Who We Are, and was hooked from the first page. If you are curious to know more about why we are each unique, and what factors influence the way we think and behave, then this book provides some thought-provoking insights. Mitchell introduces the missing third component of variance into the traditional nature/nurture debate by examining the profound effects that developmental variation from the moment of fertilization onwards can bring about. He explains with beautiful clarity that our genetic code is like a recipe; no matter how precise it is, there will necessarily be some differences in the outcome each time. You just can't bake the same cake twice. I'm no scientist, but I found this book to be both highly informative and very readable - studded with plenty 'Gosh-I-never-knew-that' nuggets of fascinating facts you will want to share. Mitchell manages to convey technical information in a lucidly informative style that makes it accessible to the non-expert. Don't be put off by the diagrams, graphs and statistics. They are used sparingly and Mitchell uses them to great effect so that they enhance the reading experience rather than detract from it. This is popular science writing at its very best.

Innate brings clarity and accessible technical detail to the most interesting and difficult questions that we are bound to face individually and as a society. From start to finish it is one of the best pop science books I have read. Can'trecommend enough.

Really thorough book and a great backdrop to non scientists but it does make demands on the reader- which is good as it stretches the old grey matter

What makes you, you? Why are you different/unique? Nature or nurture? Not a blank slate yet it can be written on . Our brains come pre-wired but not hard-wired. How come? And much more this brilliant, original, insightful book is about. Just ask a question and you'll get an answer

One of the best book on Bran development.