Dr. Leanne Tenbrinke

People with these personality traits, by virtue of being callous and manipulative, that manipulative part comes with a lot of deception.

When you're around these people, you know, you start to see what they're saying and the reality does not line up.

Thanks for having me, Mike.

Yeah, that's a great question.

So we end up using kind of lots of euphemisms for these folks in our lives.

But when I talk about a poisonous person, what I am describing is someone who's really high on what I call the dark tetrad.

So these are a particular set of personality traits.

They include psychopathy, Machiavellianism, narcissism, and sadism.

And the thing that all of those traits share in common is that they involve callousness and manipulation.

And so by virtue of that, people who come into contact with these personalities tend to be on the receiving end of that, resulting in lots of

pain, an outsized amount of harm that they cause in their social networks, and certainly can create these kinds of toxic cultures.

And where does that come from?

We have fairly good data now to suggest that these personality traits, particularly psychopathy and narcissism, which we know the most about, come from a fairly even mix of genetics and environmental influences.

So when it comes to psychopathy in particular, so these folks are characterized by that callousness and manipulation that I talked about earlier, but also impulsivity and really low remorse.

And so unsurprisingly, these folks tend to be overrepresented in, say, prison populations and engage in a whole lot of antisocial behavior, both criminal and non-criminal in nature.

And we can see these traits early in life.

So research suggests that you can detect callous and unemotional traits in particular in kids as young as about two years old.

And that suggests that there's a genetic component.

So we do know from twin studies that individuals who have a shared genetic component are more likely to share that psychopathic

type of personality than those that are less related, like fraternal twins or siblings.