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Chapter

PSYC 1000 Chapter Notes -Physical Attractiveness, Observational Error, Human Sexuality


Department
Psychology
Course Code
PSYC 1000
Professor
Harvey Marmurek

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Course: PSYC*1000 (DE)
Professor: Harvey Marmurek
Schedule: Summer, 2012
Textbook: Psychology – Tenth Edition in Modules authored by David G. Myers
Textbook ISBN: 9781464102615
Module 11: Behaviour Genetics and Evolutionary Psychology
What are our genes and how doe behaviour geneticists explain our individual differences?
The plans for your own book of life run to 46 chapters – 23 donated by your mother’s egg and 23 by your
father’s sperm. Each of these 46 chapters, called a chromosome, is composed of a coiled chain of the
molecule DNA; genes are the small segments within that form the words of those chapters (20,000 to
25,000)
oGenes can be active (expressed) or inactive
Share 96% of our DNA sequence with chimpanzees
Twin and Adoption Studies
oIdentical Twins – monozygotic egg; genetically identical
Although identical twins have the same genes, they don’t always have the same number of
copies of those genes; explains why one may be more at risk of certain illness
Most share a placenta but 1 in 3 ha two separate placentas explaining some differences
oFraternal Twins – dizygotic; womb mates
oIdentical twin with Alzheimers may have 60% risk whereas fraternal’s risk is 30%
oSeparated Twins – despite being separated for 38 years, virtually alike (Jim Lewis and Jim
Springer)
99 identical and 200 fraternal twins separated – still, separated twins were more alike if
genetically identical than fraternal
Bouchard’s critics: “if any two strangers were to spend ours comparing their behaviours
and life histories, they would probably discover many coincidental similarities
Biological Versus Adoptive Relatives
oGenetic relatives
oEnvironmental relatives
oAdoptees are more similar to their biological parents than to their caregiving adoptive parents
oThe environment shared by a family’s children has virtually no discernible impact on their
personalities
oThe genetic leash may limit the family environment’s influence on personality, but parents do
influence their children’s attitudes, values, manners, faith, and politics. A par of adopted children or
identical twins will, especially during adolescence, have more similar religious beliefs if reared
together.
Temperament and Heredity
oHeredity predisposes one quickly apparent aspec of personality – temperament, or emotional
excitability
Difficult, easy, and slow-to-warm-up
oThe genetic effect appears in physiological differences
Anxious, inhibited infants have high and variable heart rates and a reactive nervous system
Put the following cell structures in order from smallest to largest: nucleus, gene, chromosome – gene, chromosome,
nucleus
When the mother’s egg and the father’s sperm unite, each contributes 23 (chromosomes)
How do researchers use twin and adoption studies to learn about psychological principles?
Researchers compare the trait and behaviours of identical twins (same genes) and fraternal twins (sharing half their
genes – similar to any sibling). They also compare adopted children with their adoptive and biological parents.
Some studies compare twins raised together or separately. These studies help us determine how much variation
among individuals is due to genetic makeup and how much to environmental factors.
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