Behavioral Genetics - Overview

What does Molecular Genetics attempt to do?

Discover, identify, and isolate genes responsible for a variety of psychological disorders and role in normal variation of behavior (e.g., autism, ADHD, childhood behavior problems…)

Factors of heritability influences ____. Give example

Risk of acquiring a disorder

• e.g., Alzheimer disease is transmitted by an allele which is associated with a 4-times greater risk

True/False: Based on your genes, no one can say what kind of human being you will turn out to be or what you will do in life.

True

Locus

The position on a chromosome

Loci

More than one position on a chromosome

Allele

An alternative DNA sequence variant. Since chromosomes come in pairs, there are two at each loci

Genotype

The combination of alleles present at a locus

Phenotype

A term referring to a trait, feature, or characteristic

What questions can Genetics be reduced to?

How do genotypes influence phenotypes

Haplotype

The combination of alleles at different loci on the same chromosome

Homozygous

Same allele

Heterozygous

Not same allele

True/False: The number of alleles determines the number of genotypes

True

Gamete

A male or female germ cell that possess a single copy of DNA (i.e., single rather than pairs of chromosomes)

Behavioral Genetic Analysis

The approach to the study of organisms and the behavior that combines the concepts of behavior analysis from psychology, based on the knowledge or control of experience with concepts and methods of genetic analysis based on the knowledge or control of ancestry.

The goal is to identify and study genetic correlates of behavior

Behavioral Genetics

The study of the inheritance of behavioral phenotypes

Who established modern behavioral genetics?

Fuller and Thompson

Predecessors to Fuller and Thompson that help establish modern behavioral genetics

Rockefeller Foundation

• The book emerged from Jackson Laboratory (1929) by Clarence Little and supported by the Rockefeller Foundation

• Alan Gregg worked at the Rockefeller Foundation and was interested in genetics of mental illness (argued that animal studies would generalize to humans)

• Clegg and Little established a Division of Behavioral Studies lead by J.P. Scott who was interested in genetics and behavior of dogs–Scott hired John Fuller

Areas of Genetic Research

• Animal Behavior Genetics

• Population Genetics

• Quantitative Genetics

• Molecular Genetics

• Behavioral Genomics

Animal Behavior Genetics

While there’s no reason to divide behavior genetics into human and animal studies, the ability to manipulate populations and carry out directed breeding means that the field has advanced much farther in animals species

Population Genetics

A field of biology that studies changes in allelic frequencies or the genetic composition of biological populations, and the changes in genetic composition that result from the operation of various factors, including natural selection.

Focuses on composition of populations (i.e., distributions and changes in genotype and phenotype frequency in response to the processes of natural selection, genetic drift, mutation, and gene flow

Theoretical Cornerstone of Modern Darwinism

Population Genetics

Quantitative Genetics

The inheritance of those differences between individuals that are of degree rather than of kind, quantitative rather than qualitative.

Studies phenotypes that have a non-discrete distribution, i.e., cannot easily be divided into classes like Mendel’s peas

E.g., bodyweight, height

Behavioral Genomics

Understanding the structure, function, and evolution of genomes. Specific behaviors are often the result of multiple genes interacting with numerous environmental factors. This shifted researchers’ focus from individual genes to entire genomes

Functional Genomics

A bottom-up approach in molecular biology that focus on finding out how genes work. (Opposed to top-down behavioral level of analysis, which is behavioral genomics)

Trends in Genetic Research

• A shift towards genetics in behavioral science–Behaviorism detached from psychology from heredity by focusing on environmental determinants of behavior

• Analysis of publications on behavioral genetics shows that the origin can be traced to the 19th century. The modern era can be denoted by the publication of Fuller and Thompson 1960. Behavioral genetics research is permeating areas of research in fields like education, economics, political science, and sociology

Plomin et al., (2016)

Investigated replications of behavioral genetics research.

• An attempt to replicate 100 psychology studies found that 36 could be substantially replicated

• Medical research failed to replicate 41% of the 49 most highly cited papers