Gene Genie

Some years ago a colleague and friend of mine asked me a provocative question: what percent of our personality is due to genetic inheritance and what percent is due to the environment one is raised in. I was very hesitant to answer, for two reasons. One was that I didn't know the literature nearly as well then as I do now. The other was that I didn't know how to express my opinion in percentages. I knew exactly what it means to say that my brother and I are 50% related. We have a fifty/fifty chance of getting a given gene from the same parent or each of us from the other parent. I wasn't so clear on what it would mean to say that 30% of our personality was due to inheritance.

I know enough now to phrase the question in a better way. Consider two pairs of children. One pair consists of identical twins raised apart in very different conditions. The second pair consists of genetically unrelated children raised together in the same household. Which pair is more likely to be similar in personality, opinions, and behavior?

We know the answer to that question. The identical twins are far more likely to be similar to each other than the unrelated pair by almost any measure. Here is how psychologist Jonathan Haidt puts it in the May issue of Reason Magazine [it doesn't seem to be available yet to nonsubscribers].

We're not just talking about IQ, mental illness, and basic personality traits such as shyness. We're talking about the degree to which you like jazz, spicy foods, and abstract art; your likelihood of getting a divorce or dying in a car crash; your religiosity; and your political orientation as an adult. Whether you end up on the right or the left of the political spectrum turns out to be just as heritable as most other traits: Genetics explains between one-third and one-half of the variability among people in their political attitudes. Being raised in a liberal or conservative household accounts for much less.

Now I could answer my colleague's question with that one-third to one-half figure, but that wasn't really what he wanted to know. The real answer to his question is that nature is far more powerful than nurture in determining what kind of person each of us becomes.

He wouldn't have wanted to hear that. Both of us were schooled at the end of a long period in which the idea of social construction was dominant in the academy. However, he was a generation older and had lived with it longer. He was also a man of the left, and the left was firmly committed to the view that human beings come into this world as blank slates, to be written on (or socially constructed) by the collective action of other human beings.

The reason that the left was so fond of that view was that it seemed to allow for the radical reconstruction of human behavior. If we could just modify the environmental inputs by social reform, we could dramatically change the behavioral outputs and get better, fairer, and more sustainable societies. Conversely, if behavior has a significant genetic component, it might be difficult to alter it with current technologies. That is why the left has been deeply suspicious of biological explanations for social and political behavior.

If that view of the nature/nurture dichotomy were correct, the left would be finished. It is very probably not correct. Making better people by modifying the social environment requires an enormous degree of control over the social environment. That is in the first place tyrannical and in the second place hopeless. The greatest social experiment in human history (Marxism-Leninism) came a cropper wherever it was tried, and that is the least nasty thing one can say for it. Culture is far harder to modify than once was imagined by socialists.

By contrast, social reform based on good theories about innate human dispositions might well succeed without any recourse to tyrannical power. There may well be genes for attachment to one's kin and one's "in-group" and hostility to the non-related and the "out-group". There are no genes for racism, as the very idea of race is of very recent origin (not to mention being fallacious). Genes code for mental schema, and schema look for environmental clues. Learning how to manipulate the clues may be a far more promising strategy for progress than anything that environmental determinism ever had to offer.

Comments

[Bill Fleming]

This is at once one of the most interesting, and one of the most incendiary of topics, KB. It is certainly worthy of careful, well reasoned consideration and debate, but one wonders whether we as a society are emotionally and intellectually prepared for it. Even as we debate the pros and cons of contraception and what constitutes a "person" I fear bioscience and the potential consequences will always far predate society's willingness to engage them in a reasonable enough context to establish coherent social policy. For example, if curing a generational genetic disease that has plagued a family for centuries meant we had to complely reorder the genes of a given fertilized egg, destroy the old one, and implant the new one every time someone in that family chose to reproduce... well?

[Donald Pay]

Well, some people take this a bit far. Liking jazz is genetic? Not likely. Of course there are genetic components to lots of the very complex mixtures of aural reception and neural aspects of listening to music of whatever sort you can name. Some people have a better acoustical acuity than others.

Music preference is largely generational, not genetic. There is a large aspect of nurture involved, but not parental nurture. Most research points to the strong influence of music in adolescent years, when people are experiencing some distancing from parents. Whatever music you are listening to when you undergo puberty, have that first crush, fall in and out of love and experience shared adolescent goofiness, angst and tumult is what is going to be of most influence on you throughout your life. Of course in traditional societies the music didn't change quickly, but classical music styles did. Musical styles changed with some regularity ever since.

I never liked jazz until I was past adolescence. I associated the music with my father, who listened to what I considered "shit" while I preferred rock. I take that back. My mom played boogie woogie and stride piano pieces badly. I liked that, because it was the only time she would say "shit," but I didn't associate any of it with the "shit" my dad played.

[larry kurtz]

Stumbled over this today--better living through chemistry:

http://www.gizmag.com/propranolol-reduces-racism/21847/

Being satisfied, getting needs met, and copious exercise: all selected for successful reproduction.

Spring: ain't it grand?

[Ken Blanchard]

In the middle of a good fight, suddenly agreement breaks out. I agree, Bill, that we may not be mature enough as a society to be ready for the consequences of current biological research. Well, we are going to have it anyway. The ethical questions are already much with us. I continue to think that the skewing of birth ratio toward males in many Asian countries is a very big problem. I also think it very ugly that so many Indian women are walking around with one kidney, having sold the other on the open market. What will happen if we discover a compound that can extend the life of 70 year olds but can only be harvested by killing four year old girls? I shudder to think.

Donald: no one is saying that there is a gene for jazz (though, if there is, I was born with it). However, there might well be a gene or set of genes that makes it more likely that one will like jazz. The things that come out of twin studies are simply astounding.

[Mark Anderson]

Last week I said, that if "Obama agrees with anything Republicans used to be for, Republicans will be against it. I believe that's a genetic disorder" I was wrong, it's just genetics, although I prefer to look at it as a disorder. Now why are so few scientists, Republicans? Now if those Minnesotan's could have just stayed away from the Pioneer Fund.

[Ken Blanchard]

Mark, you amazing man: Republicans are all suffering from a disorder and the Washington Post is a Neo-Con newspaper. Whatever color the sky is in your world, I am sure it is no shade of blue.

[D.E. Bishop]

In the midst of this genetic discussion, which I agree is meritorious, I wonder about the exceptions.

In a family history of poverty, lack of education, mental illness, joblessness, etc., why does one child become very successful? What is it in that one that gives her strength, courage, aspiration, success?

Does genetics help us understand the exceptions? Because if science can do that, we can make exceptions become the ordinary. Wouldn't that be wonderful?

[Ken Blanchard]

D.E.B.: Yes. One of the key facts about sexual reproduction is variation. Within a single litter, there will be a range of puppies. Otherwise, natural selection would have nothing to work on.

Of course, a lot of other things make for exceptions. Some offspring are fortunate. My mother never went to college and my father had only a pharmacy degree. I did have a lot of gifted teachers from grade school on. My third grade teacher gave me a book about science when she realized I was interested. There is also the matter of individual decisions. Sometimes these make a big difference.

[Mark Anderson]

You know Ken, I just wish you were better read, than red. Read Robert Parry, he among many others has identified the Washington Post in this way: "fitting with that propaganda strategy, the Washington Post's editorial page, which is essentially the neocons' media flagship," Here are two of them, Jennifer Rubin and Fred Hiatt who hired her. Rubin in particular who has tweeted and linked to articles by Rachael Abrams of the Emergency Committee for Israel.

[Ken Blanchard]

Mark: what you mean is that the WaPo occasionally thinks outside the box in which your mind is tightly confined. I can understand why you think that that is apostasy.

[Mark Anderson]

Ken,
My sky is still blue, I don't think anything is an apostasy, I just like facts. I didn't even mention George Will or Charles Krauthammer because of course they are old school conservatives who are at the Washington Post. You really need to get out more.