PSYC 2600 Chapter Notes - Chapter 6: Human Genome Project, Behavioural Genetics, Human Genome
19 Jun 2018
School
Department
Course
Professor
Week 4 Readings
Chapter 6: Genetics and Personality
The Human Genome
Genome: the complete set of genes an organism possesses
- Human genome contains between 20 000-30 000 genes on 23 chromosomes
Human Genome Project: dedicated to sequencing the entire human genome
Controversy about Genes and Personality
- Researchers attempt to determine the degree to which individual differences in
personality are caused by genetic and environmental differences
- Many people worry that findings from behavioural genetics will be misused
Eugenetics: the notion that we can design the future of the human species by fostering the
reproduction of persons with certain traits and by discouraging the reproduction of persons
without those traits
- Example: creating a master race (Hitler)
Goals of Behavioural Genetics
Percentage of Variance: the fact that individuals vary, or are different form each other, and this
variability can be partitioned into percentages that are due to different causes
- Behaviour genetics is interested in determining the ways in which genes and the
environment interact and correlate with each other
What is Heritability?
Heritability: a statistic that refers to the proportion observed variance in a group of individuals
that can be accounted for by genetic variance
Formal Definition: the proportion of phenotypic variance that is attributable to genotypic
variance
Phenotypic Variance: observed individual differences
- The degree to which genetics cause individual differences
- Example: height, weight
Genotypic Variance: individual differences in the total collection of genes possessed by each
person
Example: a heritability of 0.50 means that 50 percent of the observed phenotypic variation is
attributable to genotypic variation
Example: a heritability of 0.20 means that the environmental component is 0.80
find more resources at oneclass.com
find more resources at oneclass.com
Environmentality: the percentage of observed variance in a group of individuals that can be
attributed to environmental differences
- The larger the heritability, the smaller the environmentality and vice versa
Misconceptions about Heritability
- it can’t be applied to a single individual
- heritability is a statistic that applies to a population at one point in time and in a
particular array of environments- heritability is not constant
If the environment changes, heritability changes
- heritability is not an absolute precise statistic- it is an estimate of the percentage of
phenotypic variances due to genetic differences
Nature-Nurture Debate Clarified
Nature-Nurture Debate: the arguments about whether genes or environments are more
important determinants of personality
- Individual Differences: there is no debate, the two are inextricably linked
- Population Differences: we can partition the differences into these two sources:
differences in genes and differences in the environment
We can make sensible statements about which is more important in accounting for the
differences
Behavioural Genetic Methods
Selective Breeding
- Only happens with animals
Selective Breeding: identifying the dogs that possess the desired characteristic and having them
mate only with other dogs that also possess the characteristic
- Because selective breeding has been so successful, it tells us that personality traits are
hereditary
Family Studies
Family studies: correlate the degree of genetic relatedness among family members with the
degree of personality similarity
- Parents share 50% of genes with their children
- Siblings share 50% of the same genes
- Grandparents share 25% of the same genes with their grandchildren
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Genome: the complete set of genes an organism possesses. Human genome contains between 20 000-30 000 genes on 23 chromosomes. Human genome project: dedicated to sequencing the entire human genome. Researchers attempt to determine the degree to which individual differences in personality are caused by genetic and environmental differences. Many people worry that findings from behavioural genetics will be misused. Eugenetics: the notion that we can design the future of the human species by fostering the reproduction of persons with certain traits and by discouraging the reproduction of persons without those traits. Percentage of variance: the fact that individuals vary, or are different form each other, and this variability can be partitioned into percentages that are due to different causes. Behaviour genetics is interested in determining the ways in which genes and the environment interact and correlate with each other.
