HERITABILITYIs it all in the GENES?

Discussion – Pair and Share What is a personality characteristic, talent,

or skill that runs in your family? Who in your family has it?

Make a little family tree chart depicting it

What is the likelihood that the trait is genetically influenced? Why do you say so?

What is the likelihood that the environment has more to do with the trait being in the family?

What is heritability?

Review… An estimate of the proportion of the total variance

in some trait that is attributable to genetic differences among individuals within a group. In other words…when looking at a group, how much of

a certain trait is genetic (vs. environmental)?

Key points: 1. Only applies to a group living in the same

environment 2. DOES NOT apply to individuals, only to variations

within a group 3. Even highly heritable traits can be modified by

the environment

How do we test heritability? Twin Studies

Why? Why identical vs. fraternal? What would

each show us? http://

www.youtube.com/watch?v=Wd5Y3-F79LY

Adoption Studies? Why?

Is your I.Q. genetic?

Intelligence Quotient For many years calculated as:

Mental age/chron. Age X 100.

Is this a good way? What about other ways of showing intelligence? Biases?

Twin studies results: Identical twins scores correlated more than fraternal

Adoption Studies: Children correlated more with biological parents than

adopted parents.

I.Q. tests as a way to further RACISM

HH Goddard’s tests on immigrants (middle 105)

The Bell Curve Remember Phrenology? Eugenics

applied science or the bio-social movement which advocates the use of practices aimed at improving the genetic composition of a population

Reading from “Race” is a Four-Letter Word: the Genesis of the Concept

Flaws in Heritability Estimates Most groups compared to mainly

white samples.

People as Tomato Plant metaphor: (pg 107!)

Genes and Personality

Heredity and Temperament Temperament = how we typically respond to our

environment

Jerome Kagan did research on infant temperaments and how that would affect people later in life 20% all babies highly reactive (excitable/nervous) 20% all babies highly NONreactive (laidback/curious) Other 60% are somewhere in between

Reactive children…mild stressors caused more action in the sympathetic nervous system, more norepinephrine (adrenaline) and cortisol (increases blood sugar)

Heredity and Personality Traits Trait

habitual way of thinking, behaving, and feeling

Raymond B. Cattell’s Factor Analysis studies supported the idea of the BIG 5 1. Introversion vs. Extroversion 2. Neuroticism/ negative emotionality 3. Agreeableness 4. Conscientiousness 5. Openness to experience

Final Thoughts

If many studies show a .5 correlation between a trait and genetic inheritance, that means the other .5 of our make-up is influenced by our environment.

Some studies my underestimate the impact of the environment

Even traits that are highly heritable are not rigidly fixed and can be modified by experience.

“The wave of acceptance of genetic influence on behavior is growing into a tidal wave that threatens to engulf the second message of this research: These same data provide the best available evidence for the importance of environmental influences” (Plomin, 1989).

Discussion Questions:

***Get into your Group Trip to the Australian Outback***

1. Just because a behavior is universal doesn’t mean that there is necessarily a genetic basis for the behavior. Geneticist Richard Lewontin point out that if 99% of Finnish are Lutheran, it doesn’t mean that Finns have a gene for Lutheranism. What other behaviors are universal (or almost universal), but are unlikely to be genetically determined?

2. Suppose that scientists developed a genetic test that would tell prospective parents whether they were carriers of a gene that contributes to obesity. Should this test be routinely offered to couples? What about a test that could predict lower than average intelligence? More generally, what are the consequences to individuals and to society of genetic engineering?

3. Evolutionary theory argues that variability is important for the ultimate survival of a species. But some would use genetic engineering to reduce variability and eliminate undesirable characteristics. What might be the possible problems with this approach? Can you imagine a scenario in which a genetic “flaw” resulting in obesity, for example, might be adaptive?

4. If a gene is found for a predisposition to antisocial behavior, should this finding change the way we deal with criminals? If so, how?