Behavior Genetics

Epigenetics

Gene-Environment Interaction

the study of environmental influences on gene expression that occur without a DNA change

environmental factors can switch genes on or off

an epigenetic mark is an organic methyl molecule that is attached to part of a DNA strand. It instructs the cell to ignore any gene present in the DNA segment, and thus prevents the DNA from producing the proteins coded by that gene

diet, drugs, and stress can affect these types of molecules

Heritability

if you walk around barefoot often, you will develop callused feet

genes are self-regulating and react

people with identical genes but differing experiences will have similar but no identical minds

the proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied

Behavior Genetics

DNA

individuals who study the relative power and limits of genetic and environmental influences on behavior

Interested In...

a complex molecule containing the genetic information that make up chromosomes

the occasional variations found at particular gene sites in human DNA

Nature vs. Nurture

Identical Twins (Monozygotic)

Genes

Example

the longstanding controversy over the relative contributions that genes and experiences make to the development of psychological traits and behaviors. Today's science sees traits and behaviors arising from the interaction of nature and nurture. Nature works on what nature endows.

Depression can be both a brain disorder and a thought disorder.

Is a child smart because their parents were smart and they inherited the same genes, or are they smart because they were sent to a good school?

Chromosomes

threadlike structures made of DNA (deoxyribonucleic acid) molecules that contain the genes

humans contain 23 from their mother and 23 from their father (grand total of 46)

extra chromosome results in down syndrome

twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms

same genes, but not always same number of those genes

extraversion and neuroticism are more similar

Human Genome

the biochemical units of hereditary that makes up chromosomes; segments of DNA capable of synthesizing proteins

20,000-25,000 genes in humans

can be active, meaning expressed, or inactive

the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes

Fraternal Twins (Dizygotic)

Separated Twins

Biological vs. Adoptive Relatives

twins who develop from seperate fertilized eggs, They are genetically no closer than brothers and sisters, but they share a fetal environment

30% increased risk of getting Alzheimer's if your fraternal twin has it

Molecular Genetics

separated twins are more alike if genetically identical

in some instances, identical twins who grew up apart are just as similar to those who grew up together

the sub field of biology that studies the molecular structure and function of genes

seeks to identify specific genes that influence behavior

goal is to find some of the multiple genes that deal with body weight, sexual orientation, and extraversion

can pinpoint genes that influence learning disorders, depression, schizophrenia, and alcohol use disorder

people who grow up together do not resemble each other in personality, no matter if they are biologically related or not

extraversion and agreeableness is more similar between adoptees and their biological parents

the environment shared by a family's children has virtually no discernible impact on personalities

most adopted children thrive, are more self-giving, and often score higher on intelligence tests than their biological parents

Behavior Genetics Predicting Individual Differences