Nature vs nuture How much of what we become is genetically determined and how much is environmental ?

Learning Outcomes By the end of the session you will be able to: Understand the nature of genetics and their influence on development Be aware of the connection between genetics, health and pre- disposition to illness

The view that humans acquire all or almost all their behavioural traits from "nurture" was termed tabula rasa ("blank slate") by philosopher John Locke, and proposes that humans develop only from environmental influences.

The history of genetics Inheritance 1880 Human genome 2003 Genotypes Phenotypes James D. Watson and Francis Crick determined the structure of DNA in 1953, using the X-ray crystallography work of Rosalind Franklin and Maurice Wilkins that indicated DNA had a helical structure (i.e., shaped like a corkscrew)

genetic disorder library - Utah University http://learn.genetics.utah.edu/content/begin/traits/predictdisorder/

Genetic mutation Agents that damage DNA Radiation Chemicals in the environment Drugs viruses Types of DNA Damage Deamination Mismatches Breaks and crosslinks All four of the bases in DNA (A, T, C, G) can be covalently modified at various positions. One of the most frequent is the loss of an amino group ("deamination") — resulting, for example, in a C being converted to a U.

In the living cell, DNA undergoes frequent chemical change, especially when it is being replicated (in S phase of the eukaryotic cell cycle). Most of these changes are quickly repaired. Those that are not result in a mutation. Thus, mutation is a failure of DNA repair. Next slide All four of the bases in DNA (A, T, C, G) can be covalently modified at various positions. One of the most frequent is the loss of an amino group ("deamination") — resulting, for example, in a C being converted to a U.

Heritability Heritability is a concept that summarises how much of the variation in a trait is due to variation in genetic factors. In many cases, it has been found that genes make a substantial contribution, including psychological traits such as intelligence and personality. Yet heritability may differ in other circumstances, for instance environmental deprivation Examples of low, medium, and high heritability traits include: High heritability Medium heritability Low heritability Blood type Weight Specific language Eye colour Religiosity Specific religion

Heritability does it depend on other variables ? Davis, O.S.P, Haworth, C.M.A., Lewis, C.M., & Plomin, R. (2012). Visual analysis of geocoded twin data puts nature and nurture on the map. Molecular Psychiatry, 17, 867-874 DOI: 10.1038/mp.2012.68

The ethical dilemmas of this information ? The Human Genome project It is 2010, and Joe Schmoe has been charged with assault. The physical evidence supporting his guilt is overwhelming and he pleads guilty. In preparation for his sentencing hearing, Joe's lawyer asks him to undergo genetic tests to determine whether he carries any of four genetic mutations that have been associated with violent behaviour. The tests, while controversial, show that Joe's DNA does, in fact, contain all four mutations. Based on these results, Joe's lawyer will argue that Joe should be sent to a psychiatric facility rather than to state prison. He claims that because Joe's genetic status predisposed him to this violent act, it would be unfair to sentence him as a criminal for behaviour over which he had essentially no control. Questions: If you were the judge at Joe's sentencing hearing, how, if at all, would the results of this controversial genetic test influence your decision? How would your decision be influenced if Joe had only 1 of the 4 mutations associated with violent behavior? What would be your decision if Joe was shown to suffer from a mental illness such as schizophrenia? How come? If Joe gets sent to prison and tries to get released on parole fifteen years later, should the fact that he may have a genetic predisposition to violent behavior be used to keep him in prison, even if his behaviour has been consistently good during his incarceration? In the future, should all newborn babies be screened to determine if they have genetic mutations that could be linked to violent behaviour? How come?

Further debates This is a complex debate because so much is still unknown There are also many sub divisions to this debate On the nature side; what is genetically inherited from birth and what is genetically determined following environmental exposure ? On the nurture side there is the structure versus agency debate i.e. socialisation versus individual autonomy. Is the evidence produced by studies in the last century which demonstrate the mother and family as highly influential mediators of nurture less relevant today when we are wildly exposed to other’s from an early age The Nurture Assumption, author Judith Harris