Saturday, June 6, 2009

Nature, Nurture, or Both?

Boys with the "warrior gene" are more likely to join gangs and act violently.

That's the result of a new study by researchers at Florida State University. Without getting all technical on you, the gene is a variant of the monoamine oxidase A gene (MAOA gene). That gene produces monoamine oxidase A, an enzyme that breaks down brain chemicals like serotonin and dopamine. (I'm starting to feel a little like Sarah Webb here.)

The "warrior gene" variation produces more momoamine oxidase A, causing increased breakdown of serotonin and dopamine. Interesting, from a chemical perspective, because serotonin and dopamine are two of the brains' "feel good" chemicals. Warriors, it seems, don't exactly have an abdunance of "feel good" chemicals. (Perhaps this also explains why that particular gene variant is linked to smoking and gambling.)

In 2006, a scientist got into trouble for suggesting that the "warrior gene" predisposes the Maori of New Zealand to violence. According to the scientist, Maori men are twice as likely to carry the gene as their European counterparts.

Which may be true, but if there's anything I've learned, it's that genes aren't a guarantee.

I myself carry a gene variant: I have a BRCA2 mutation, which predisposes me to breast and ovarian cancer, just as an MAOA variation supposedly predisposes certain men and boys toward violence.

But if there's one point my genetic counselor made perfectly clear, it's that my BRCA mutation is not a guarantee. Having the mutation increases my risk of cancer, and drastically so. But it's possible to have the mutation and never get cancer.

No one knows exactly why or how that works yet -- and if they did, trust me, I'd do everything I could to make sure I ended up in that population -- but they suspect it's because cancer is multicausal. Having the mutation alone isn't enough; whether or not you develop cancer could depend on a slew of other things, like environmental influences, other health conditions and whether or when you had children.

I suspect the same is true with the "warrior gene." Simply having the gene will not cause you to join a gang or pull the trigger. Having the gene and living in a gang-infested area with no family support? Well, that's something else.

All I'm saying is this: genes are not destiny. No matter what your sons' genes hold, you matter -- and probably a lot more than you think.


  1. Swear Greg and I were just talking nature vs nurture with the whole adoption thing! But I will email you about that as I'm sure everyone doesnt need to read my comment about it :) Bottom line I agree genes don't mean certainty

  2. Hey Jenny,

    This is a great post. Come check out my blog, I just wrote a post on the presence of a parent.

  3. Honestly, to observe my sons and their friends, I would have guessed all boys have the "Warrior Gene".

    I believe that environment plays a much bigger role in determining whether a male joins a gang or acts violently.