Heredity and Temperament
• In human beings, individual differences in
temperaments emerge at birth or early in life.
• These differences influence subsequent
personality development.
• They include:
– reactivity
– soothability, and
– positive or negative emotionality
• Heritability refers to the proportion of the total
variation in a trait that is attributable to genetic
variation within a group.
• Behavioral-genetic data from twin and adoption
studies suggest that the heritability of many adult
personality traits is about .50.
• Genetic influences:
– create dispositions and
– set limits on the expression of specific traits
• Even traits that are highly heritable are often
modified throughout life by:
– circumstances
– chance, and
– learning
• Conclusions that “biology is destiny” or our fates
are controlled by our genes are not warranted.
• Having a genetic predisposition does not
necessarily imply genetic inevitability.
• The very definition of a trait is that it is consistent
across situations.
• But people often behave inconsistently in different
circumstances.
• The reason for people’s inconsistency is that in
different contexts, different behaviors are:
– rewarded
– punished, or
– ignored
• According to social-cognitive learning theory,
personality results from the interaction of the
environment and aspects of the individual.
• This process is known as reciprocal determinism.
• Children are shaped by interactions involving:
– varied experiences that affect each differently
– chance events that cannot be predicted
• In human beings, individual differences in
temperaments emerge at birth or early in life.
• These differences influence subsequent
personality development.
• They include:
– reactivity
– soothability, and
– positive or negative emotionality
• Heritability refers to the proportion of the total
variation in a trait that is attributable to genetic
variation within a group.
• Behavioral-genetic data from twin and adoption
studies suggest that the heritability of many adult
personality traits is about .50.
• Genetic influences:
– create dispositions and
– set limits on the expression of specific traits
• Even traits that are highly heritable are often
modified throughout life by:
– circumstances
– chance, and
– learning
• Conclusions that “biology is destiny” or our fates
are controlled by our genes are not warranted.
• Having a genetic predisposition does not
necessarily imply genetic inevitability.
• The very definition of a trait is that it is consistent
across situations.
• But people often behave inconsistently in different
circumstances.
• The reason for people’s inconsistency is that in
different contexts, different behaviors are:
– rewarded
– punished, or
– ignored
• According to social-cognitive learning theory,
personality results from the interaction of the
environment and aspects of the individual.
• This process is known as reciprocal determinism.
• Children are shaped by interactions involving:
– varied experiences that affect each differently
– chance events that cannot be predicted
