One of the things that’s a challenge in understanding
how something as simple and small as a gene can affect something as complicated as human
behavior is that it takes a long time for those effects to be manifest.
And we had been doing a study of marriages that started 20 years ago, it started in 1989.
So one of the things that we noticed as we started studying couples — especially over
time is that some couples are in these relationships that are very emotionally difficult. A lot
of anger and sadness and contempt. And the marriages just get really miserable. Others
have similarly toxic environments, but they seem to do OK.
So this is not what we were expecting. We were expecting the emotions to pretty much
determine how happy people were with their marriage, regardless. But it wasn’t the case.
And we started thinking that maybe the answer lies in their genes. Slight differences in
the genetic make up of individuals could incline them to be more or less sensitive to the emotional
quality of their marriage. So we’re interested in a gene that regulates serotonin in the
brain. A lot of the drugs that are used to treat depression act on the serotonin system
in the brain. This is clearly a very important chemical for determining the nature of our
emotional lives. So the serotonin transporter gene has two commonly occurring variations:
one is the long allele and one is the short allele. So when we got into this area, the
prevailing view was that if you had the short alleles, it was just bad. There were a number
of studies that suggested that people who had the short alleles had a higher risk for
developing depression and a number of terrible outcomes. But the pendulum was starting to
shift to think about this not as a risk gene, but as a sensitivity gene. So our thought
was maybe it’s not that you’re just going to have bad reactions but you’re going to
have more of the reactions that you’d expect given the environment you were in. People
with the short alleles look at cartoons or funny films — they laugh more. In a situation
that’s embarrassing, and we had a kind of a karaoke task, people with the short alleles
they get more embarrassed. So it didn’t seem that the short allele produced a particular
kind of emotional response, it just produced a bigger emotional response across the board.
And so that was the clue to us that when we looked at marriage, that we would find that
the short allele people would be doing really well in marriages that were emotionally positive
and really poorly in marriages that were emotionally negative. So people with the long alleles,
what’s determining whether they’re satisfied or dissatisfied with their marriages?It could
be any of a millions things, you know, it might be how much money they’re making. It
might be whether their kids are doing well. But it wouldn’t be this sort of emotional
substrate of their relationship. So it’s important to step back and ask:well, how big of difference
is this? Could I see it with the naked eye? And I think you can’t. I think these genetic
variants produce slight biases. Having the short allele may make our emotional responses
just a little bit bigger. And just one incident isn’t going to make much of a difference,
but if you start thinking of like 20 years in the life of a marriage and about hundreds
of emotions every day — In the aggregate this becomes something that really does make
a difference. So how about if we could kind of reconstruct a personal genome and we knew
enough about the function of each gene so we could really start to get a picture of
how all these genes affected us and how they made us the person that we are. But we are
so far away from that now. We are just at the very beginning of being able to understand
a few of these genes. So stay tuned, we’re just getting started. As complicated, as mysterious,
and extraordinary as relationships are — there is science that can be done here. There are
these understandable forces that are driving even these most complicated kind of parts
of our lives and the value of good science and careful science is when it really starts
to help us understand some of these mysteries.