A counter-intuitive idea –
That our genes and our experiences interact with, and have an impact on the development and/or functioning of, each other.
How do our genes impact our experiences?
They predispose us – but don’t cause us – to experience, respond to our environment in a certain way. Text example (p.32): “What we inherit is not a fear of snakes but a predisposition to learn a fear of snakes – a nature for a certain kind of nature.”
How do our experiences impact our genes?
Our genes are designed to (p.32): “…take their cues from everything that happens to us from the moment of our conception.”
What are hox genes and what do they do?
Hox genes are a small group of genes that set up the body plan – how the body will be physically formed. This applies to every creature, from flies to human beings.
What are genomes?
(P.33): “The genome is not a blueprint for constructing a body. It is a recipe for baking a body…the development of a certain human behavior takes time and occurs in a certain order, just as the cooking of a perfect soufflé requires not just the right ingredients but also the right amount of cooking and the right order of events.”
How do our genes operate?
They are switched on and off in various parts of our bodies at different times, by segments of DNA called promoters.
How does the makeup of promoter affect our mental or physical development? Promoters are made of strings of DNA that can be longer or shorter and can vary to a greater or lesser degree in substance, as represented by geneticists with strings (“paragraphs”) of letters of the alphabet. Just a small difference in the makeup of a promoter can cause a huge difference in the expression of a hox gene – on how, when and where they are switched on and off in the body. Human learning, it turns out, (p.32): “…consists of nothing more than switching genes on and off.”
Why we turn out the way we do – Examples:
• Language – Specific genes open and close on a critical window of time, during which human beings can learn to speak. However adults must be talking to the child during this critical interval; just having the right genes, alone, is not enough. If no one talks to the kid during that critical learning interval, (s)he will always struggle with speech.
• Love – We humans have a specific chunk of DNA, about 460 letters long, that gives us the potential to fall in love after having the “right” experience (if any of you figure out what that is, please let me know!)
• Antisocial behavior – Childhood maltreatment is not enough to cause people to act criminally. The other essential ingredient = a promoter that regulates the activity of a particular gene, called the “monoamine oxidase A” gene. People in whom that gene is highly active are virtually immune to the criminogenic effects of maltreatment. People in whom the gene is “low-active” developed into much more decidedly antisocial individuals if maltreated – and – even if they were not mistreated at all, they still became antisocial, but to a slightly lesser degree. In the research sample, the men with low-active genes who were mistreated as kids were responsible for 4X their share of rapes, robberies and assaults. Ergo: maltreatment is not enough; you’ve also got to have the low-active gene. And, having the low-active gene is not; you also have to be maltreated. (Research from Terrie Moffit, of London’s King’s College, on a group of 442 New Zealand men followed since birth.)
• Homosexuality – Gay men are more likely to have older brothers than are hetero men or lesbians. The investigator who did the study hypothesizes that some sort of immune reaction develops in the mother with each male pregnancy; growing stronger with each male birth, which affects certain key genes during the fetus’ brain development – and this in turn boosts the boy’s potential to be attracted to his own sex. A lot of...