4. Gene-Environment Relationships

About this Lecture

Lecture

In this lecture, we think about how our genes and the environment can relate, and combine, to create a final ‘output’ (phenotype), focusing in particular on: (i) the example of height, noting that research shows that 60-80% of variation in people’s height can be attributed to genetic variation; (ii) the environmental factor of diet, proposing that nutritional intake impacts the extent to which our genetic potential for height is expressed; (iii) the key distinction between genotype and phenotype, explaining that our genotype can lay out a range of heights that we might achieve, while our phenotype is the observable characteristic of objectively how tall we actually are; (iv) the phenotype as being where we see the role our environment has played on the expression of our genetic tendency for a particular characteristic; (v) Caspi and colleagues’ 2003 study, implicating long and short alleles of the 5-HTT gene with depression outcomes in the face of negative life events; (vi) differentiating passive, active, and evocative correlations between genetic and environmental influences.

Glossary:

Genotype – The genetic composition of an individual organism as a whole, or at one specific position on a chromosome.

Phenotype – The observable characteristics of an individual, such as morphological or bio- chemical features and the presence or absence of a particular disease or condition.

A passive genotype-environment correlation – The association between the genotype that a child inherits from their parents and the environment in which that child is raised.

An active (or selective) genotype-environment correlation – The association between an individual's genetic propensities and the environmental niches that an individual selects.

An evocative (or reactive) genotype-environment correlation – The association between an individual's genetically influenced behaviour and others' reactions to that behaviour.

Course

In this course, Dr Lydia Kearney (University of Kent) explores the nature ‘versus’ nurture debate in psychology. In the first lecture, we preface the course by proposing the removal of ‘versus’, predicated on the origin of any human behaviour being too complicated to be explained by just one set of factors. In the second lecture, we take a deep dive into the nature side of this debate, introducing Mendelian genetics and explaining the concept of heritability. In the third lecture, we explore the nurture side of this debate, outlining a timeline, from the ancient philosophers who proposed the tabula rasa, to modern research on environmental factors that impact aggressive tendencies. Next, we bring in a modern perspective on the interactions between environmental and genetic factors when explaining phenotype expression. In the fifth and final lecture, social anxiety is used to exemplify how environmental and genetic factors, as well as their interactions, can predict the prevalence and experience of the condition.

Lecturer

Dr Lydia Kearney is Deputy School Director of Education in the School of Psychology at the University of Kent. Dr Kearney’s research areas of interest are social anxiety and experiences of mental imagery, particularly how the two interact and impact attention and interpretation biases. Some of Dr Kearney’s recent publications include 'Observer perspective imagery in social anxiety: effects on negative thoughts and discomfort' (2011) and 'The intra and interpersonal effects of observer and field perspective imagery in social anxiety' (2013).