Natural Science Forum / Biology / Biology / October 2004

A Genetic Mechanism for the Four Temperaments Proposed by Keirsey
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Introduction
~~~~~~~~~~~~

Keirsey has proposed that personality comprises temperament and
character, and that temperament dominates behaviour and is present at
birth as result of traits inherited from the biological parents [1].
Keirsey has proposed that there are four temperament types; Artisan,
Guardian, Idealist and Rational. I propose here a genetic mechanism
for these temperaments.

The Theory
~~~~~~~~~~

I propose that human temperament type is determined by a mechanism
analogous to that which is responsible for human blood type [2]
(though I do not propose that temperament type and blood type are
associated).

I propose that temperament type is based on the presence or absence
of two change-drivers -- Realism and Idealism -- which determine the
way in which we use change to persue our goals.
                                                    R   I
There are thus three possible alleles on each gene: I , I  and i --
henceforth represented here by R, I and O respectively.

There are thus six possible gene-pairs -- genotypes -- for an
individual: RR, RI, RO, II, IO and OO. However, in the cases of RR
and RO the only change-driver present is R, thus both these genotypes
produce the same temperament. Similarly, the II and IO genotypes
produce the same temperament. I am proposing a mechanism of
co-dominant alleles, thus in the case of RI -- where both alleles are
present -- both alleles are represented in the temperament of the
individual.

Thus, out of six possible genotypes there are four unique types of
temperament;
  Type R -- only the R change-driver is present;
  Type I -- only the I change-driver is present;
  Type RI -- both change-drivers are present;
  Type O -- neither change-driver is present.

I propose that these four temperaments correspond to Keirsey's four
temperaments:
  The R temperament to Keirsey's Artisan;
  the I temperament to Keirsey's Idealist;
  the RI temperament to Keirsey's Rational;
  the O temperament to Keirsey's Guardian.

Artisans are driven to persue their goals by realism, which gives
rise to their pre-occupation with the 'here and now' and their
opportunistic nature. Idealists are driven to persue their goals by
idealism, which gives rise to their desire to strive for what would
be ideal, but with little regard for the practicalities. Rationals
are driven to persue their goals by both realism and idealism.
Rationals are thus required to strike a balance, which gives rise to
their pragmatism and problem-solving ability. Guardians are not
driven to persue their goals by either realism or idealism, hence
their preference for avoiding change and keeping to tried and tested
ways of achieving their goals.

Since each biological parent donates one of their two alleles to
their child, the possible combinations of parent and child genotype
are:

  Parent 1          Parent 2            Child
  --------          --------            -----

  Artisan (RR/RO)   Artisan (RR/RO)     Artisan (RR/RO)
                                        Guardian (OO)

  Artisan (RR/RO)   Idealist (II/IO)    Rational (RI)
                                        Artisan (RO)
                                        Idealist (IO)
                                        Guardian (OO)

  Artisan (RR/RO)   Rational (RI)       Artisan (RR/RO)
                                        Idealist (IO)
                                        Rational (RI)

  Artisan (RR/RO)   Guardian (OO)       Artisan (RO)
                                        Guardian (OO)

  Idealist (II/IO)  Idealist (II/IO)    Idealist (II/IO)
                                        Guardian (OO)

  Idealist (II/IO)  Rational (RI)       Idealist (II/IO)
                                        Rational (RI)
                                        Artisan (RO)

  Idealist (II/IO)  Guardian (OO)       Idealist (IO)
                                        Guardian (OO)

  Rational (RI)     Rational (RI)       Artisan (RR)
                                        Rational (RI)
                                        Idealist (II)

  Rational (RI)     Guardian (OO)       Artisan (RO)
                                        Idealist (IO)

  Guardian (OO)     Guardian (OO)       Guardian (OO)

Testing the Theory
~~~~~~~~~~~~~~~~~~

This theory can be tested. Parent combinations of particular value
are those where:
  Both parents are Guardians -- only Guardian children can result;
  One parent is a Guardian -- a Rational child cannot result;
  One parent is a Rational -- a Guardian child cannot result.

Several conditions would need to be satisfied for the test to be
valid:
  Both parents are the biological parents of the children --
  established by DNA testing;
  the temperament sorter is designed to test directly for the four
  temperaments;
  the sorter is completed by the individuals themselves -- no
  testing by observation.

Keirsey published two sorters which produce a four-temperament result
[1]. The Keirsey Four-Temperament Sorter is suitable for testing the
theory. The Keirsey Temperament Sorter II is not suitable for testing
the theory because it is basically a Myers-Briggs temperament test,
the result of which is converted to one of the four temperaments
using correlations Keirsey has proposed (but not proved).

References
~~~~~~~~~~

[1] Keirsey D, Please Understand Me II, First Edition, Prometheus
   Nemesis Book Company, 1998.
[2] I would like to donate blood -- do they need all blood types or
   just certain ones?,
   http://science.howstuffworks.com/question593.htm, HowStuffWorks
   Inc.