1. Genes and Behaviour By Mr Daniel Hansson

2. “The Jim Twins” - Bouchard (1979)  Twins were separated at birth and reunited at age of 39  Both drove Chevrolets and enjoyed stock car racing  Both had a background in police work and had worked part-time as deputy sherifs  Both chain-smoked and took holidays in Florida  Both had a workshop in the basement of their house where they built furniture  Both had been married twice. The first wives were called Linda  Both had sons that were called James Alan  Both had dogs named Toy  Both had similar medical histories (identical blood and pulse pressure and haemorrhoids)  Both had put on 10 pounds at the same time earlier in their lives

3. Chromosomes  Threadlike structures in the cell  Composed of double strands of DNA and proteins, containing the genes.  In humans, there are 23 pairs of chromosomes

4. DNA  The molecule that encodes genetic information.  DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides. The four nucleotides in DNA contain the bases: adenine (A), guanine (G), cytosine (C), and thymine (T).  Duplicates itself during meiosis (division of cells)

5. Genes  The basic unit of heredity  Made up of sequences of “building blocks” called amino acids.  Humans possess about 30,000 genes, each regulating production of various proteins.  Genes functions in pairs  Variants of genes are called alleles  Alleles can be either dominant: (Will be expressed whenever it occurs) or recessive (not as dominant

6. Genotype, Phenotype, Mutation  Genotype: The genetic code which an individual carries in the DNA of their cells  Phenotype: The observed characteristics of the individual, based on the combination of genotype and environmental influences  Mutation: A change in the genetic material of a cell. While rare, mutations can result in new characteristics which may be transmitted to descendants of the original cell.

7. How Genes Influence Behavior  Genes influence behaviour indirectly. There is usually more than one genGenes influence the production of proteins that affect the anatomy (e.g. brain structure) and physiology (chemical processes) of the body  e involved in a behaviour  Some behaviours are more genetically influenced than others  There is an interaction between environmental, biological, cognitive and genetic factors in the development of behaviour (e.g. diathesis-stress model)

8. Types of Correlation Studies in Gene Research  Concordance studies/twin studies: Measure the degree of similarity in characteristics, such as intelligence, between genetically related and less genetically related individuals  Molecular genetics (e.g. Caspi et al., 2003): Compare genetic material from individuals with a certain characteristic with individuals without the certain characteristic

9. Concordance  The probability that a pair of individuals, e.g. a twin pair, will both have a certain characteristic, given that one in the pair has the characteristic.

10. Guess the Concordance Rates (0- 100 %) of Identical Twins for the Following Behaviors  Depression  Phobias  Memory  Personality  Intelligence  Happiness  Homosexuality  Schizophrenia  Religious values, political beliefs and vocational interests  Aggression  Alcoholism

11. Concordance Rates for Identical twins  Depression: 30 %  Phobias: 30 to 50 %  Memory: 0 to 80 %  Personality: 20 to 45 %  Intelligence: 50 to 80 %  Happiness: 60 to 80 %  Homosexuality: 40 to 100 %  Schizophrenia: 50 to 85 %  Religious values, political beliefs and vocational interests: 14 to 50 %  Aggression: 40 %  Alcoholism: 65 %

12. Activity Calculate concordance rates between you and a randomly chosen classmate on:  TV series you like to watch  Food that you like to eat  Friends that you have in common  Movies that you like  Music  Any other interests

13.  Some behaviors run in families (e.g. Schizophrenia, Depression)  Some behaviors can be bred true in animals  Related species have similar behavior (e.g. Chimpanzees)  Behavior is often species specific Evidence that Genes Influence Behavior

14. Criticisms of Gene Research on Behavior  Issues with self report of twins  Researcher expectancies  Possibility of unrepresentative samples  Problems with generalisability to other samples  Correlational studies cannot infer cause- effects of behaviour

15. Benefits of Gene Research on Behavior  Contributes to our understanding and insight of psychological phenomena (e.g. personality, homosexuality, depression)  Usefulness (can be used to develop medication and treat people with hereditary diseases, e.g. schizophrenia, PKU)