PSYC 1101 Chapter Notes - Chapter 4: Y Chromosome, Ejaculation, Epigenetics
Notes on Nature Nurture and Human Diversity
Behavior Genetics: Predicting Individual Differences
● Behavior geneticists → Study differences in heredity and environment
Genes: Our Codes for Life
● Chromosome → composed of DNA → genes
● Environment can turn genes on and off
● Provide codes for proteins
● Genome → instructions for making an organism
● Humans very similar to chimpanzees
● Traits can be affected by various factors
Twins and Adoption Studies
Identical Versus Fraternal Twins
● Identical → from same egg → genetically identical
● Differences in twins:
○ Have the same genes but not necessarily the same number of those genes
○ Twins can have different placentas
● Fraternal → from different eggs
● Shared genetic experiences
● More behaviorally similar
● Even separated twins have similarities
● Identical twins more alike than fraternal
Biological Versus Adoptive Relatives
● Environmental vs genetic parents
● Personality more like biological or adopted parents?
● Some traits more like one set of parents than another
● Religious involvement is genetic
● Psych disorders more likely in non-adoptive families because parents are not screened
so neglect and abuse is higher
Temperament and Heredity
● Temperament → emotional reactivity and excitability
● Temperament tends not to change, even from before or right after birth
● Gene regulates serotonin
Heritability
● Heritability → how much from genes and how much from environment
● Variation among people
● Environments becoming more similar so heredity = more differences
● Heritable individuals don’t imply heritable group differences
Gene-Environment Interaction
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Document Summary
Behavior geneticists study differences in heredity and environment. Identical from same egg genetically identical. Have the same genes but not necessarily the same number of those genes. Some traits more like one set of parents than another. Psych disorders more likely in non-adoptive families because parents are not screened so neglect and abuse is higher. Temperament tends not to change, even from before or right after birth. Heritability how much from genes and how much from environment. Environments becoming more similar so heredity = more differences. Adaptations such as feet callouses occur because of an environment. Molecular genetics studies molecular structure and function of genes. Molecular behavior genetics find some of many genes that influence complex traits. Searching for triggers that switch genes on and off. Epigenetics studies environmental effects on expression of genes. Environmental factors switch genes for certain things on and off. Gender socially influenced traits by which men and women are defined.