Unit 3-C (C):
Heritability and
Molecular Genetics
Mr. McCormick
A.P. Psychology
Do-Now
(In Journal)
 How
much of your behavior do you
attribute to biology?
 How
much of your behavior do you
attribute to your environment?
 Why?
Heritability

Heritability:



The proportion of variation among individuals that we can
attribute to genes
Varies, depending on populations and environments being
studied
Measured from 0-1:


0 [0%] (low heritability): Influenced by environment
1 [100%] (high heritability): Influenced by genes



E.g.: If the heritability of intelligence in a given population/environment is
40% (moderately low), then genetic influence explains 40% of differences in
intelligence among that specific population
Herit: Inherit
Ability: Capability
Heritability:
Genetic or Environmental Differences?

Observe the image of “Plant Heritability”

What can explain variations of height among plants grown
in the left flower pot?


What can explain variations of height among plants grown
in the right flower pot?


Describe the Heritability (High/Low) of height variations among
plants grown in the left flower pot.
Describe the Heritability (High/Low) of height variations among
plants grown in the right flower pot.
What can explain variations of height among plants grown
in both the left and right flower pots?

Describe the Heritability (High/Low) of height variations among
plants grown in both the left and right flower pots.
Heritability

Can you think of a real-life example, in which
differences within a specific population
were highly due to environment (low
heritability)?

Can you think of a real-life example, in which
differences within a specific population
were highly due to genetics (high
heritability)?
Nature Vs. Nurture

Genes and environments work together in influencing
human thought and behavior:


Genes may predispose individuals to various physical and
psychological traits, though one’s environment may affect
the extent to which these traits develop
Interaction:


The interplay that occurs when one factor (heredity) affects
another factor (environment)
E.g. Someone with a predisposition to aggression may elicit
others to treat them more defensively
Nature Vs. Nurture
Can you think of an
example of an interaction
between a “Nature” factor
and a “Nurture” factor?
Molecular Genetics

Molecular Genetics:

The subfield of biology that
studies the molecular structure
and function of genes

“Bottom Up” approach to
understanding biopsychology

E.g. Identifying genes that
influence one’s introversion vs.
extroversion
Homework

Chapter 4 Quiz: “Nature, Nurture, and Human
Diversity”

Unit 3 Test: “Biological Bases of Behavior”

Chapter 6 Outline: “Sensation and Perception”

Unit 3 Project: “3-D Brain Model”