Why are their individual differences in behavior and personality?

Behavior geneticists Scientists who study the genetic bases of individual differences

Why are some great people great athletes while others are can’t be no matter how hard they try?

Heritability A statistic Estimates the proportion of total variance in a trait that is attributable to genetic difference within a group

Heritability Expressed as a proportion Between 0 and 1

example: HEIGHT highly heritable means when all other things are the same, some will be taller b/c of genetics

example: politeness low heritability differences in politeness are due to upbringing not genetics

Nature versus Nurture Need to know the following to really understand the issue

1 can only apply heritability to a specific group in a specific environment

2 heritability estimates do not apply to individuals can’t tell exact reason why MJ is so good at basketball

3 even highly heritable traits can be modified by the environment

How does one compute heritability? Can’t just look at family history they share same environment too

How does one compute heritability? look at adopted children compare traits of child with those of biological parents and adoptive parents

How does one compute heritability? compare identical twins with fraternal twins if identical twins are more similar than fraternal than difference must be due to genetics

How does one compute heritability? Compare identical twins separated at birth Similarities should be due to genes