Amy Harmon's DNA is not definitive
Before I dig into Amy Harmon's recent NYTimes cover story about exploring her own DNA, two caveat/disclosures:
1. I am not constantly critiquing NYTimes stories in this blog because the Times does a particularly bad job of explaining the science behind genetics, talent and intelligence. As with nearly every subject, they do a much better job than most. I refer to them so often because I that's the daily paper I read, and because it's the paper of record. Because they're so good, they bear the burden of the most scrutiny.
2. Amy Harmon is a great science and technology reporter. I have long admired her work, and have talked to her a few times as she was reporting tech stories over the years. I think we also have some friends in common.
Ok, now onto her piece.
This is a good story that needed to be written. In a light and entertaining way, it begins to illustrate the thicket we're all stepping into as cheap consumer genetic tests become available. For those of you who haven't yet read the piece, Harmon writes about her experience in receiving a state-of-the-art genetic report about herself. From her report, she is able to see if she is more or less predisposed to a number of diseases and traits. This information carries a lot of emotional baggage and a ton of very practical concerns ranging from lifestyle choices to insurability.
But the story also leaves out what I think is the most important part: a true explanation of what "predisposition" and "risks" actually mean in this context. The heart of this story, for me, is when Harmon reassures herself about a supposed genetic disposition for poor verbal memory.
"Should I be recording more of my interviews? No, I decided. I remember what people say. DNA is not definitive."
What does that mean -- that DNA is not definitive? And what does it mean that Harmon has three high-intelligence mutations out of a possible six? What does it mean that her particular gene sequence "meant that I had been eligible for the 6-point I.Q. boost when my mother breast-fed me"? What does it mean that she is 23% more likely than average to have a heart attack?
We need to start with an essential -- and widely misunderstood -- truth about genes. While our number and basic sequence of genes does insure that each of us develops into a human being rather than a hippopotamus, our particular genes themselves do not dictate what we become. They are not individual blueprints of our future brains, bodies, personalities, talents, intelligence, creativity, or athleticism.
Instead, from the moment of conception, we become our individual selves through a dynamic process of interaction between genes and our environment. Genes are not instruction code telling our cells what to do; rather, they are switches getting rapidly turned on and off by external factors. That switching process subsequently tells cells how to behave.
Don't take my word for it. Listen to Michael Meaney, Director of the McGill Centre for the Study of Behaviour, Genes and Environment:
"There are no genetic factors that can be studied independently of the environment, and there are no environmental factors that function independently of the genome. Phenotype emerges only from the interaction of gene and environment. The search for main effects is a fool's errand. In the context of modem molecular biology, it is a quest that is without credibility."
That's what Harmon means when she says "genes are not definitive." It's actually a lot more interesting than that. Genes are just one part of the equation of our lives. They do not give us heart attacks, or Alzheimer's disease, or higher or lower I.Q.'s. It's the gene-environment interaction that leads to those things.
In other words, there is no nature vs. nurture. There is only there is only n N u A r T t U u R r E e , a tangled fusion of the two, inextricably intertwined, catalyzing one another.
So when someone says that DNA is not definitive, that may be the most profound understatement printed in the New York Times all year. When Harmon reveals that she has half the known high-intelligence mutations, this actually tells her absolutely nothing about her intelligence capabilities. Intelligence is something that comes out of a developmental process; it is not an innate ability.
Except for extreme and very limited cases, genes do not limit what we can become. They play an important role, but there's actually no evidence that they set true upper or lower limits on our capabilities. To the contrary, all the evidence seems to indicate that our limitations come out of the developmental process that is our lives.
Which means that Harmon is giving in to myth and not science in this paragraph:
"But I had decided not to submit my daughter’s DNA for testing — at least not yet — because I didn’t want to regard anything about her as predestined. If she wants to play the piano, who cares if she lacks perfect pitch? If she wants to run the 100-meter dash, who cares if she lacks the sprinting gene? And did I really want to know — did she really want to know someday — what genes she got from which parent and which grandparent?"
First of all there is no perfect pitch gene. Musicologists now think that perfect pitch is something available to all or most of us given the right developmental circumstances. More here.
There is also no sprinting gene. There are mutations that, under absolutely-optimal lifestyle and training conditions, will help make some faster sprinters than others. But there is no "predestined" genetic sequence that is going to make her daughter fast or slow.
With very rare exceptions, there is no predestined anything in our lives. Almost none of us will ever know our true limitations in any area unless we push ourselves to extraordinary lengths.
A lot of this probably sounds bizarre to an intelligent audience raised in a nature-vs.-nurture paradigm. Certainly Harmon owes us no apology for her articulate explanation of the science as it has been explained to her. But there's an enormous gap now in what the leading developmental biologists understand and our antiquated popular understanding of what genes do. That's what I'm trying help correct in my book.
