Just a few things before we begin the next chapter, a bit about...

Behavioral Genetics

Nature v. Nurture As an introduction to the study of development, let’s review. What is this? Is it really nature versus nurture?

This issue is better stated as how does nurture impact nature. How does the environment impact the genetic make up of an individual.

Behavioral genetics studies the role played by inheritance in mental abilities, temperament, emotional stability, and such.

Transmission of hereditary characteristics is achieved by a biological process Some terms to know Chromosomes- Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique. DNA- DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria. Genes-A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make molecules called proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.

Punnett Square

Brown eyed or blue eyed

Genetic make-up is genotype. Expression of genes is phenotype.

Transmission of incorrect number of chromosomes can results in individuals with chromosomal abnormalities. Transmission of incorrect number of chromosomes can result in an individual with chromosomal abnormalities. Down’s Syndrome Turner’s Syndrome Klienfelter’s Syndrome

Some abnormalities result from recessive genes. Tay-Sachs Syndrome Albinism PKU Huntington’s Disease Color Blindness Hemophilia

Behavioral Genetics Research Extrapolation from selective breeding in rats, dogs and other animals Adoption Studies Twins Studies Monozygotic Twins (MZ) Dizygotic Twins (DZ)

What is heritability?

Heritability Heritability is a concept that summarizes how much of the variation in a trait is due to variation in genetic factors. The statistical definition suggests that heritability is the proportion of phenotypic variance attributed to genetic variance. Or, the extent to which genetic individual differences contribute to individual differences in observed behavior (phenotypic) Heritability is a POPULATION CONCEPT. It tells us nothing about an individual. A heritability of.40 informs us that, on average, 40% of individual differences in shyness may in some way be attributed to genetic differences. It DOES NOT MEAN 40% of shyness is from genetics and 60% from the environment.

What are inherited traits?

Inherited Traits These are traits that are manifested in the individual Examples?

What are molecular genetics? Field of biology that studies how the genes are transferred from generation to generation.

Recall: What is evolutionary psychology?

Evolutionary Psychology In a nutshell... All organisms, including humans, are “gene- producing machines” with the basic motivation of perpetuating their own genetic pool. In short, our genes predispose us to act in ways that enhance their chances of surviving and spreading. This fundamental motive underlies all of our thinking and behavior.