Tuesday, 16 June 2020

Book Review: Inheritance, Sharon Moalem (2014)

I’ve had this book in my collection since buying it soon after its publication, probably at Books of Buderim on the Sunshine Coast. Until recently it sat unread on one or another of my bookshelves.

Subtitled ‘How Our Genes Change Our Lives, and Our Lives Change Our Genes’, it’s a fun read, and for someone, like me, who knows little about genetics and epigenetics (the second word meaning how genes are affected by environment) there’s plenty in the book to wonder at – in fact “wonder” is like a talisman that kept repeating in my mind as I was reading, this branch of science so new and so complex that it seems to embody something about the future itself. Though it reads a little, at times, like an invitation to get your genome sequenced.

It’s becoming clear to specialists that inheritance works in subtle ways, and that, for example, trauma suffered by a person in one generation can be passed down to his or her children. All of the ideas we thought we possessed about inheritance are set to be thrown out the window. And because genetics and the health practices that are allied to it are so new, the laws that define how information contained in your genome can be used is often either new or non-existent.

Some of what Moalem writes – at least what he says about the law and the economics of healthcare – will be irrelevant to many readers because the US health system is so different from what applies in most developed nations.

And each country will be in the process of coming to terms with the new reality as it reflects advances in genetics and epigenetics. How health insurance companies access such patient information might, for all I know, be completely different in the US from how it happens in Australia. In fact, it’s almost guaranteed to be the case. For readers of this blog located in Helsinki or Agadir, I cannot offer much advice, but rest assured that change is on the way.

While you don’t need any background information to engage with this book as most terms are explained, it might help to be acquainted with a few key concepts, such as “allele”. Wikipedia might help those who lose track of things when unfamiliar words are used, but in the book there is usually enough secondary detail to enable you to orient yourself so that you can follow the narrative. “Allele” is a specific term that is used to talk about inheritance, as this passage from a web page demonstrates.
Although an individual gene may code for a specific physical trait, that gene can exist in different forms, or alleles. One allele for every gene in an organism is inherited from each of that organism's parents. In some cases, both parents provide the same allele of a given gene, and the offspring is referred to as homozygous ("homo" meaning "same") for that allele. In other cases, each parent provides a different allele of a given gene, and the offspring is referred to as heterozygous ("hetero" meaning "different") for that allele. Alleles produce phenotypes (or physical versions of a trait) that are either dominant or recessive. 
Genes are found on long strings (chromosomes) of chemicals (nucleotides) in each of your somatic cells – the cells that make you up apart from reproductive cells (I told you this would be complex). The four chemicals – so few! – are used to construct your code, the code which is duplicated each time a cell is made. During the production of your originary cells, which will become the embryo from which your body will be formed, if one of the chemicals is copied incorrectly, either put in the wrong order or exchanged for another of the four – one marker out of the billions that make up your individual code – then you can have a disease that can lead to death, or that can lead to a change that will dramatically impact your life. And just because your parents didn’t show a trait, doesn’t mean that you will be exempt:
Somatic cells contain two alleles for every gene, with one allele provided by each parent of an organism. Often, it is impossible to determine which two alleles of a gene are present within an organism's chromosomes based solely on the outward appearance of that organism. However, an allele that is hidden, or not expressed by an organism, can still be passed on to that organism's offspring and expressed in a later generation.
What is of interest perhaps to most people is how invisible traits can suddenly express themselves in the children of two individuals, neither of whom shows any sign that they have a disease. It is not, however, possible for such a trait to express itself when it is recessive. Moalem talks about such things and provides examples, but because of the nature of the material I am pretty sure I won’t be able to meaningfully talk about the even more complex subject of epigenetics – though it is such an interesting field of enquiry – for a long time to come.

It’s clear to specialists like Moalem, but it’s probably news to you, that life experiences can affect the genetic makeup of your children. So just as characteristics that in an earlier age might have been slated down to morality are now understood to be part of “just the way you are made”, the way we understand our responsibilities to the children we are destined to love so much, is changing. Random acts can have consequences not just for your own future but, indeed, in the lives of people yet to be born. Do you really need to have that second drink?

Family is something we hide from most people; you only get to know such things about a person after meeting with them under the right circumstances a number of times. But family is at least something that we are willing to discuss with friends. We should be talking about inheritance more, as it is to become more prevalent as part of our lives. We all want to be healthy and we all want our children – if we are lucky enough to be able to conceive – to be happy and well.

Recommendations for similar books to read are welcome. The author had help writing ‘Inheritance’, and though his prose is flexible and accurate the book contains some errors (“free reign” …?) and awkward expressions, all of which might’ve been eliminated by better editing.

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