Biological LOA Genetic Inheritance

Key Question With reference to relevant research studies, to what extent does genetic inheritance influence behavior?

Intelligence Take the IQ Test How much is intelligence based on genes? What types of skills was the test that you took trying to measure? Considering the definitions above, do you think that the test was measuring intelligence?

Intelligence How much is intelligence based on genes? Binet Gottfredson, 1994 Judgment, otherwise called "good sense," "practical sense," "initiative," the faculty of adapting one's self to circumstances ... auto-critique. A very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience. It is not merely book learning, a narrow academic skill, or test-taking smarts. Rather, it reflects a broader and deeper capability for comprehending our surroundings—"catching on," "making sense" of things, or "figuring out" what to do. Gardner, 1993 A human intellectual competence must entail a set of skills of problem solving — enabling the individual to resolve genuine problems or difficulties that he or she encounters and, when appropriate, to create an effective product — and must also entail the potential for finding or creating problems — and thereby laying the groundwork for the acquisition of new knowledge. It's not how smart you are, it's how you are smart.

Nature vs Nurture Nature Nurture Inherited characteristics Passed on by the genes of parents Environmental influences Learned through people and situations

Genetics vs. Environment How can we measure this? How can we measure the extent of genetic influence on behavior? Genetics vs. Environment Twin Studies Adoption Studies Pedigree Studies

Concordance Rate Twin studies MZ Twins DZ Twins Monozygotic twins Identical Twins Share 90% of genes Dizygotic twins None-identical twins Share 50% of genes Concordance Rate

Why study adopted children? Adoption studies Importance of adoption studies Can compare the behaviour of the child to the adoptive parents’ behaviour (environment) and to the biological parents’ behaviour (genes) Using MZ and DZ twins, can compare the behaviour of the adopted siblings (environment) to their twin sibling (genes) Why study adopted children?

Adoption scenarios Scenario 1 Scenario 2 Child shows sign of aggression Adoptive parents don’t show any sign of aggression Biological parents show sign of aggression Child shows no sign of aggression Adoptive parents don’t show any sign of aggression Biological parents show sign of aggression Genes or environment? Genes or environment?

PEDIGREE studies Family Tree analysis Look for trends in data over multiple generations

Limitations Lots of variables: Too many variables that come into play when comparing families. (especially when it comes to adoption and reared apart twin studies.) Researcher Bias: Researcher can choose the family to study – bias tor prove what they want not meant to favour one outcome when doing research but in this hotly debated topic they often do. Correlation vs Causation This only gives proof that genes and behaviour are correlated but doesn’t prove causation

Intelligence Bouchard and McGue (1981) Bouchard et al. (1990) Read p. 53 – 54 (Crane) Gather information on these three studies: Bouchard and McGue (1981) Bouchard et al. (1990) Scarr and Weinberg (1977)

Questions 1. What is meant by “g”? What types of skills are tested to measure it? 2. What is a “meta-analysis?” 3. Explain two strengths of the Minnesota Twin Study (Bouchard et al, 1990). 4. According to Bouchard, 70 percent of our intelligence may be genetic in origin. What does that mean? 5. Explain how Scarr & Weinberg’s study challenges Bouchard’s findings. “G” is the term used by psychologists to describe “general intelligence.” It is focused on spatial reasoning, divergent thinking and verbal fluency. Divergent thinking is a thought process or method used to generate creative ideas by exploring many possible solutions A meta-analysis is an analysis of several similar studies in order to come up with a trend. For example, looking at several studies on IQ and finding that studies consistently showed a correlation between parents’ IQ and their offsprings’ IQ It is not a research method, but a statistical analysis of several different studies. List: It was a longitudinal study which has generated a lot of data. It is the most cross-cultural study to date. The mean age of participants was 41 years old. Not only students, but more representative of a larger population. Triangulation: There was method triangulation - that is, extensive use of testing and interviews. They also looked at twins raised together, twins raised apart and biological siblings raised together. Thus, there was data triangulation 4. It means that there is a strong genetic basis for our level of intelligence. It also means that environmental factors play a significant role. The researchers argue that we have a disposition to a certain level of intelligence which is then “activated” by environmental stimuli. This is known as the Diathesis-Stress approach to explaining behaviour 5. The researchers found no significant difference in IQ’s between adopted and “natural” children in families. The families clearly had an effect on the intellectual development of both children. There are, however, several limitations of this study: The study was only done on wealthy, white and middle class families who had high IQs. It is not clear whether this would be true in other family environments. We do not know the age at which the children were adopted, or what their family histories were before adoption. In this way, the type of family they came from may have biological influence on their levels of intelligence. It does not establish the “extent” of genetic inheritance, so it may very well be that this is not really a challenge to Bouchard’s research.

Fill the table! Use the articles on Moodle to help you fill the table below Genetic Influence Counter Claims Aggression Creativity Criminal Behavior Sexuality

Make a plan… With reference to relevant research studies, to what extent does genetic inheritance influence behavior?

Vanessa George News Report One of the most high profile recent criminals in the UK. Some of you may find the information in the video upsetting.

What influences Vanessa George to be a criminal? Working in pairs discuss all the potential influences that may have had an impact Place these factors in order of influence (the largest to the least)

How much does each have an influence? What do you think? Do you agree with this?

Adoption scenarios Scenario 1 Scenario 2 Child shows sign of aggression Adoptive parents don’t show any sign of aggression Biological parents show sign of aggression Child shows no sign of aggression Adoptive parents don’t show any sign of aggression Biological parents show sign of aggression Genes or environment? Genes or environment?

Research support Meta-analysis (1994) Coccaro et al. (1997) Mason and Frick (1994) Approximately 50% of the difference between anti-social and non- antisocial behaviour could be caused by genes Estimated that: 1. Genes accounted for more than 40% of aggression 2. Environment accounted for around 50% of physical aggression and 70% of verbal aggression

Ishikawa & Raine (2002) Read through the handout on the 2002 study. Complete a key study sheet.