All right. Let's talk about yet another
theory of personality called the biologic theory. But let me first
start off by saying that there are many
variations to this theory. Some relate more
specifically to the brain. And others, like the
evolutionary approach, the evolutionary
psychology approach, is more concerned with
behavior rather than traits. So for example, the
evolutionary psychology theorizes that males and
females have different mating strategies that influence
the costs associated with passing on
genetic material. For example, men have
lots of sexual partners, but women are more selective
due to the costs of pregnancy. Now, this case I
just said is probably the most dominant psychological
and biological theory to date. And Buss is one of the major
psychologists associated with that. Now, taking all of this
aside, the biologic theory suggests that important
components of personality are inherited. So that's the key word. Important components are
inherited or determined in part by our genes. And I'm not talking about
those things we wear. But I'm talking
about the things that are buried deep within
our cell's nucleus. And to study biologic and
genetic effects on personality, researchers always
turn to look at twins, because twins studies are used
in many psychological theories to tease out environmental
versus genetic characteristics. Now, more specifically, they
look at identical twins. And that's because they have
the same genetic makeup. So that will eliminate
one factor of variation. So they look at identical
twins who were raised apart from each other or in
different environments. Now, results showed that even
though the twins were reared separately at an
early age, they still had similar personalities. Certain traits
that we give credit to the trait theory
for categorizing were more influenced by
heredity than others were. And one example is the
social potency trait. And social potency is the
degree to which a person assumes leadership and mastery
roles in a social situation. So this was found to be
common in both twins that were raised separately. And another trait,
called traditionalism, which is the tendency
to follow authority, was also shown to be
common with both twins. But at the same time,
there were other traits that had weaker
genetic components. And some examples of this
is the trait of achievement. It was stronger in one
twin versus another. And same with closeness. So some researchers
have even gone further to look at specific genes to try
and relate to our personality. One example is that people with
a longer dopamine-4 receptor gene are more likely
to be thrill seekers. So basically, if
you have this gene, you may love roller
coasters and probably want to skydive one day. Hey, that sounds a lot like me. No. But don't think that just
because you have a gene, you're destined to
have that personality. We all know that. So just because you have a
longer dopamine-4 receptor gene doesn't mean you will be
a thrill seeker for sure. There are a lot of other things,
such as environmental factors, that are coupled with genes
that account for variation. Like looking back at this
case of the identical twins. Obviously, there are parts
of their personality that we can attribute to
how they were reared and differences in their
environment growing up. Now, another key word
to know with this theory and many other theories
is the word "temperament." Now, temperament is
an innate disposition. And that's why I bring it
up with the biologic theory, because of that word, "innate." Innate usually means brought up
by genetics, or it's inherited. So temperament is anything from
our mood to our activity level. And it's usually consistent
throughout our life. And temperament is not
solely just associated with the biologic theory. It's also associated with
several other theories, including the trait theory. So biologic principles can
underlie important concepts in many personality theories. So overall, the important
takeaway of this tutorial is that our inherited
genes, to some degree, lead to our traits,
which then in turn lead to our behavior
or our personality. But this isn't an end-all,
be-all relationship. Our genes don't always
determine our total personality. There has to be other things
that account for this. And that includes
environmental factors.