Monozygotic (Mz )
and Dizygotic (Dz
) 
twins are examined for the concordance of traits
and characteristics. Essentially this is a correlation of traits examined
through survey or psychological tests.
Twin
Studies
Monozygotic (Mz
) and Dizygotic (Dz
) twins are examined for the concordance of traits
and characteristics. Essentially this is a correlation of traits examined
through survey or psychological tests.
Mz twins share 100% of their genes while Dz twins share on average 50% of their genes, same for siblings and parents or children.
Studies suggest that some traits such as extroversion and neuroticism have higher concordance rates for Mz than Dz twins. Propensity for divorce?
Separated twins:
Naturalistic quasi experiment where Mz twins are separated at birth and reunited
in adulthood.
E.g., Jim and Jim
, Oskar and Jack
or Gerald & Mark
.
(Jim & Jim -each married a woman named Linda, divorce them and then married women named betty, named their sons James Alan and James Allan, both named their boy-hood dogs "toy" they drank the same brand of beer and chain-smoked the same brand of cigarettes, both were deputy sheriffs and worked at McDonalds and pumped gas, enjoyed woodworking and stock-car races, chewed their finger nails and vacationed on the same Florida beach.)
Critique:
-Any two people will have chance similarities (chance)
-Twins adopted to similar homes by common agency (environment)
-had been together after reunion prior to testing
Personality
appears to be more similar to biological than adopted parents,
but values attitudes, manners, faith and politics are more similar to adopted
parents (Wade et al. 2007).
Temperament
Emotional reactivity is similar across ages (0-9mo);
as
is inhibited or social type (4 mo - 2 yr);
emotional intensity (4 -12 mo,
3-21 yr).
Comparative studies with monkeys show heredity predisposes temperament.
Walter Mischel (2004) and socio-cognitive approach: looking at how behaviour is a result of persons and situations. We interpret personality or people's behaviours against how we think certain situations should go.
Zimbardo (2008) discusses Mischel's work on delay of gratification in young children (age 4) and predicts how they will respond to later issues in life based upon their style of time perspective. youtube
In the Time paradox, Zimbardo considers how present (hedonism) and future (delay) style lead to differences in education, taking drugs, etc. [listen on line in d2l (or Moodle) to the time paradox lecture]
Now that all of this has been said there is the newly developing field of epigenetics.
Epigenetics is a field that suggests that the environments of our parents or ancestors has an impact on us!
This is reflective of the Theory of Acquired Inheritance put forth by Jean-Baptiste Lamarck (1744-1829) ( a theory that people have said was falsified for many years now)!
Additionally the "New Biology" of Bruce Lipton (4) indicates that biology and perception (of the environment) are very closely related in terms of how "perception"( or beliefs) changes biology. See also parts 5, 6 & 7 (implications to cognition and health).
We adjust our genes to fit the envirnoments that we live in (based on perception)!
He also discusses how "nature" can also be impacted by "mind" in Beyond Darwin
