Heredity, Genes & Chromosomes, and Nature vs. Nurture Brain & Behavior Heredity, Genes & Chromosomes, and Nature vs. Nurture

Heredity: Our Genetic Heredity is transmission of characteristics from parents to offspring - Physical traits – height, hair, & eye color - Psychological traits like – shyness, leadership, & aggressiveness; interested in arts & crafts Disorders such as anxiety, depression, schizophrenia, bipolar disorders, & alcoholism

Genes & Chromosomes Genes are the basic building blocks of heredity - Traits are pairs of genes, with one gene in each pair inherited from each parent * Blood type (single pair of genes); Intelligence (combinations of genes) Chromosomes found in DNA - Most normal human beings have 46 chromosomes (organized into 23 pairs) - Psychologists try to find clues of psychological traits in how genes are paired * Without 46, physical & behavioral disorders result

Nature-Nurture Debate Nature refers to what people inherit – biological groundwork that prepares a person to develop in certain ways. Nurture refers to environmental factors – what a person is exposed to in life; family, education, culture, living conditions, & everyday individual experiences How much of who we are is found in our genes (nature) verses how we are raised & environmental conditions (nurture)?

How Much Do You Have In Common With Your Relatives? Identical Twins: 100% of their genes Parents & Children: 50% of their genes Brother & Sisters: 50% of their genes Your Aunts & Uncles: 25% of their genes Your 1st Cousins: 12.5% of their genes

Human Behavior Genetics Family Studies based on the assumptions that if genes influence a trait, close relatives should share that trait more often than distant relatives because close relatives have more genes in common. For example, schizophrenia occurs in only 1 to 2% of the population. Siblings of schizophrenia are about 8 times more likely, & the children are about 10 times more likely, to develop the disorder. * However, families also share environments.

Twin Studies & Fraternal Twin Studies Twin studies & fraternal twin studies have provided evidence for the habitability of a # of behaviors, ranging from verbal skills to aggressiveness, to mannerism such as the strength of a handshake to depression & anxiety. For example, when one identical twin develops schizophrenia, the chances that the other twin will develop the disorder are about 50%. For fraternal twins, the chances are about 15%. * The higher rate exhibited by twins, particularly identical twins, suggests that heredity plays a crucial role in schizophrenia.

Adoptive Studies Adoptive studies focus on children who were adopted at birth & brought up by parents not genetically related to them, & evidence for the habitability of intelligence & some forms of mental illness & in behavior thought to be solely determined by environmental influences. For example, of the 47 people whose adopted mother suffered from schizophrenia, 5 adoptees subsequently suffered as well. * With a control group, however, there was not a single case.

Psychological & Physical Traits Environmental: Nurture Record both psychological & physical traits that you share with members of your family! Identify if the traits are nature or nurture. Psychological & Physical Traits Heredity: Nature Environmental: Nurture Color of my eyes * 2. Work ethic 3. Height 4. Personality 5. Sense of Humor 6. Hair Color 7. Athleticism 8. Physical Make-up 9. Intelligence 10. Determination