What scientific idea can lead to a certain personality types A, B, C, D?

The Goldsmith Theory of personality types was first
published in the 1950s.  That study divided personality into a binary of high-strung
A-types and easy-going B-types.  The study's initial purpose was to find a correlation
between personality type (behavior and attitude) and coronary disease.  The type D
personality was defined by Johan Denollet in the late 1990s and attempts to further
refine Goldsmith's theory.  He finds that over 20% of the population has what he calls a
Type D personality, characterized by social inhibition, worry and anxiety.  Around 50%
of Denollet's cardiac patients fall into this type D category, linking stress with heart
disease.