... contributions of genes & environment in the development of behavior
•Hold genetic make-up constant to study effects of the environment alone (VT=VE)
•cross-fostering experiments & twin studies
•Hold environment constant & explore effects of genes alone (VT=VG)
•selective breeding experiments
•use of ...
Sex-Linked (AKA X-Linked) Disorders
... B. Co-dominance: AB Blood Type
C. Incomplete: Sickle Cell Anemia
D. Sex-Linked Inheritance
Fragile X Syndrome
-Most common inherited cause of mental
-Symptoms begin to surface in early
Genetics and Personality
... Contains between 30,000 and
All are located on 23 pairs of
The body contains roughly 100
trillion copies of the human genome
The Human Genome Project
Voting: In Your Genes? - James Fowler
... environmental factors such as whether
more of the identical than fraternal twins
were living together, which might inflate
their degree of similarity. The researchers
concluded that the correlation for voting
was much higher between pairs of identical
(.71) than fraternal (.50) twins. From this
Nature, Nurture and Human Diversity
... – Identical twins show more similar
• Correlations for identical were .63, .62, and .53
• Correlations for fraternal were .12, -.13, and -.03
M3 - Mr. Haley
... Fraternal Twins
• Twins who developed from separate
eggs; the are genetically no more
similar than other siblings, but they
share a fetal environment
• Called dizygotic twins
... Twin studies
– Environmental relatedness?
• Monochorionic (2/3 MZ), dichorionic (1/3 MZ, all DZ)
... and their adoptive parents, or adopted children and
their genetic parents
Understanding Heritability and Epigenetics
... Francis Galton, who was Charles Darwin's cousin. Heritability is a group statistic that makes no sense when
applied to one person. Heritability is the extent to which differences in the appearance of a trait across several
people can be accounted for by differences in their genes. Heritability does ...
Genetics and Behavior Principles of Gene Action and Heredity
... environment combine to influence organism’s
– Variations in environment can have large effects on
development of phenotype
– Gene-environment interaction is a two-way process
– Genetic factors play a role in the environments that
individuals inhabit and how they shape their
Chapter 14 – Key Terms
... Activity – temperament that affects the vigor or intensity of responses; also refers to individual
differences on a dimension that ranges from hyperactivity to extreme inactivity (p. 327)
Behavior genetics – study of the role of genes in social behavior and personality (p. 323)
Dizygotic twins – fra ...
PowerPoint Presentation - The Genetics of Behavior
... a particular group living in an particular
Heritability estimates do not apply to
individuals, only to variations within a
Even highly heritable traits can be
modified by the environment.
... members with the degree of similarity in personality trait.
If a trait is highly heritable, family members with greater
genetic relatedness should be more similar to one another
on the trait than family members who are less closely
Problem: Members of a family who share the ...
46 chromosomes: 23 from each parent
... Canalization Principle (Waddington, 1966): genes can limit development to a
small number of outcomes.
infant babbling is mostly genetic for the first 10 months or so
sometimes environmental influences over-ride genetic endowment (e.g.
ducks preferring chicken calls)
Range-of-Reaction Principle: ...
... that came later? What dates are associated with the major fossil hominids? Where were
the Australopithecines found?
How are human feet different from those of other hominids?
What assumptions must be met for a population to be in Hardy-Weinberg Equilibrium?
Name four processes that can change gene f ...
Behavior Genetics: Predicting Individual Differences
... Adoptees tend to have more similar personality traits to
their birth parents than to their adoptive families
Furthermore, siblings (biologically related or not) do not
tend to show the same personality traits.
But, children (adopted or not) tend to show similar
attitudes, values, morals, political t ...
... and tested people raised in poverty whom I knew from observation had suppressed IQs because
of their poverty.”
Turkheimer’s study differed from previous twin IQ studies in two important ways. First, he
identified a data source comprised of over 600 twin pairs, of which a substantial proportion
Heritability of IQ
Research on heritability of IQ infers from the similarity of IQ in closely related persons the proportion of variance of IQ among individuals in a study population that is associated with genetic variation within that population. This provides a maximum estimate of genetic versus environmental influence for phenotypic variation in IQ in that population. ""Heritability"", in this sense, ""refers to the genetic contribution to variance within a population and in a specific environment"". There has been significant controversy in the academic community about the heritability of IQ since research on the issue began in the late nineteenth century. Intelligence in the normal range is a polygenic trait. However, certain single gene genetic disorders can severely affect intelligence, with phenylketonuria as an example.Estimates in the academic research of the heritability of IQ have varied from below 0.5 to a high of 0.8 (where 1.0 indicates that monozygotic twins have no variance in IQ and 0 indicates that their IQs are completely uncorrelated). Some studies have found that heritability is lower in families of low socioeconomic status. IQ heritability increases during early childhood, but it is unclear whether it stabilizes thereafter. A 1996 statement by the American Psychological Association gave about 0.45 for children and about .75 during and after adolescence. A 2004 meta-analysis of reports in Current Directions in Psychological Science gave an overall estimate of around 0.85 for 18-year-olds and older. The general figure for heritability of IQ is about 0.5 across multiple studies in varying populations. Recent studies suggest that family environment (i.e., upbringing) has negligible long-lasting effects upon adult IQ.