BrainStuff Classics: Is There a Gene for Infidelity?

Some animals mate for life -- and others decidedly don't. Learn what researchers have discovered about cheating by studying voles and humans alike in this classic episode of BrainStuff, based on this article: https://science.howstuffworks.com/life/genetic/good-excuse-or-is-there-actually-cheating-gene.htm

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio. Hey
brain Stuff, Lauren Vogelbaum here with a classic episode from
our archives. There are lots of ways for humans to
conduct romantic or sexual relationships, be they monogamous or non monogamous,
and we are not the only animals that vary these practices.

(00:22):
Today's question is could part of this behavior be genetic?
Hey brain Stuff, Lauren Vogelbaum. Here, consider the humble prairie vowle.
Unlike of species, prairie voles are faithfully monogamous. Their lives
may be short, they're an easy snack for hawks and snakes,
but once two prairie voles mate, they are bonded until

(00:44):
the end. Not so with the prairie voles close genetic cousin,
the philandering montane vole. Montane voles form weak social bonds
and prefer the mating strategy of use them and lose them.
The stark differences in mating behavior between these two voles
species have made excellent subjects for decoding the genetic roots
of sexual monogamy and infidelity. According to a number of studies,

(01:06):
prairie voles have more receptors in their brains for a
hormone called vasopressin, which is believed to play a key
role in pair bonding. Not only do the faithful prairie
voles have more of these receptors than their cheating cousins,
but the receptors are located in a part of the
brain that's closer to their reward center. So when prairie
voles mate, their bodies produced vasopressin, which causes their brains

(01:28):
to reward the vole couple with a flood of pleasurable emotions,
sealing the social bond. The brains of montane voles, on
the other hand, have far fewer vasopressin receptors and therefore
make much weaker connections between pair bonding and pleasure. So
it's on to the next conquest. The location and sensitivity
of hormone receptors is dictated by our genes, which naturally

(01:49):
leads to the question could the urge to cheat on
our romantic partners be partly a product of our genes?
Are some of us walking around with prairie vole brains
while others are stuck with the wandering eye of a
montane vole. The real stories about the roots of infidelity
and monogamy are far more complicated than whether you have
a cheating gene. Human sexual behavior is the product of

(02:10):
countless influences and interactions, from our early relationships with our parents,
to social norms around sexuality, to yes our genetic predispositions.
We spoke with Justin Garcia, and evolutionary biologist and sex
researcher at the pioneering Kinsey Institute at Indiana University. He said,
we are never prisoners of our biology, but it does

(02:31):
explain why some people wake up with somewhat different motivations
in these areas than other people. The influence of these
different genetically based motivations is difficult to quantify, but study
by Australian researcher Brendan ze Each offers some intriguing clues.
Z Each surveyed these sexual habits of nearly seven thousand,
four hundred twins and siblings in Finland and found that

(02:53):
nine point eight percent of men and six point four
percent of women had had more than one sexual partner
in the past year. But the fascinating finding was that
these sets of identical twins with identical genomes reported the
exact same levels of fidelity, while fraternal twins and regular
siblings did not. That indicates that the variations and genes
are powerful enough to influence sexual behavior beyond other environmental factors.

(03:17):
In fact, each put a number on it. Our genes
account for roughly sixty three percent of infidelity in males
and four percent in females. Vasopresident isn't the only hormone
that's been linked to varying levels of monogamy and infidelity.
Oxytocin is another hormone released during sex and also during
childbirth and nursing that strengthens social bonds and female roles

(03:38):
with more oxytocin receptors are also more likely to mate
for life. Garcia at the Kinsey Institute conducted a landmark
study of dopamine receptors and sexual straying. It's long been
established that people with fewer or weaker dopamine receptors engage
in riskier behavior, drug and alcohol abuse, and gambling to
get the same dopamine rush that the average person might

(03:59):
get from eating a snickers. Garcia tested a hundred and
eighty one participants, some of whom carried the weaker D
four variant of the dopamine receptor. He found the people
with the D four receptor were more likely to report
sexual infidelity, and when he looked at all participants who
cheated in the study, those with the D four receptor
were far more likely to do it multiple times. For Garcia,

(04:22):
the genetic evidence points to a more nuanced understanding of
what it means when somebody cheats in a relationship. He said.
The classic explanation is that they're not really in love,
but maybe they're more motivated by other feelings of sensation, risk,
and novelty. Today's episode is based on the article good

(04:45):
Excuse or is there actually a cheating gene on how
stuff works dot com written by Dave Rouse. Brain Stuff
is production of I Heart Radio in partnership with how
stuff works dot Com, and it is produced by Tyler Clay.
For more podcasts, my heart Radio is that the I
heart Radio app, Apple Podcasts, or wherever you listen to
your favorite shows. H