CHAPTER 3 NATURE VS NURTURE How do families

CHAPTER 3 NATURE VS. NURTURE How do families, friends and culture affect the way we live?

Behavior Genetics - Study the relative effects of genes and environment on behavior - The nature vs. nurture debate

Genetics in Brief � � Genes – biochemical units of heredity that make up a chromosome Chromosome – Threadlike structures made of DNA molecules that contain genes (46 total, 23 from each parent) DNA (deoxyribonucleic acid) – complex molecule that contains genetic information that makes up chromosomes Cell -> Nucleus -> Chromosomes -> DNA -> Genes

Human Genome � � Genes made up of nucleotides (A, T, C, or G) Genome – complete instructions for making an organism consisting of all genetic material in its chromosomes Humans have about 30, 000 different genes Does anyone know the animal humans are most genetically related to?

Predisposition � � � Genes are responsible for predisposing our appearance and behavior, not concretely determining either. Predisposition – a situation that allows something else to occur but doesn’t necessarily cause it to occur; “Her genetic makeup left her with a predisposition to develop Alzheimer's. ” Mutations – random error in gene replication that lead to a change in genetic code

Charles Darwin and Evolution � � Natural selection – the idea that , among the inherited trait variations, those contributing to survival will most likely be passed on to future generations Adaptation – species changing genetically to better survive in their environment

Class Discussion � � � What correlation does economic/social status of a country have with reproduction rates worldwide if any? Why do people in poorer countries have more babies? And should they have more babies? Is this natural selection at work here? Why or why not?

Twin Studies: Score one for Nature � � � Identical twins – twins that develop from a single fertilized egg and then split in half; are genetically identical Fraternal twins – twins that develop from separate eggs; no more related genetically than normal siblings Twin studies have discovered that identical twins are strikingly similar is intelligence, attitude and even brain waves!

Adoption Studies: Score another for nature! � � � Studies of adopted children show that they exhibit similar personality traits of their biological parents However, adopted children tend to be smarter, more productive and more successful than their biological parents Nurture is back in the game!

Environment Matters � � Are parents to blame for success/failure of children? Studies say “not really”. Siblings raised together tend to be as different personality-wise as two random people on the street.

Early Learning and Brain Development � � � For our brains to reach their developmental potential, early experience is CRITICAL. Children raised in abusive homes tend to be less intelligent that children raised in loving environments. Score one for nurture!

Peer and Parent Influence � � Peers hold a heavy influence on the behaviors of individuals (i. e. smoking, drinking, promiscuity ) Bandwagon phenomenon “Fitting In” Parents influence behaviors of children by supplying them the environment from which they have to work within (i. e. parents “choose” which neighborhood to live in)

Cultural Influence � � Culture – shared attitudes and beliefs of a group passed on from one generation to the next. Norms – understood rules for accepted and expected behavior; prescribe “proper” behavior Individualism – giving priority to one’s goal over the goals of the group Collectivism – giving priority to the group’s goal over the goal of the individual

T. O. D. � Scientists have done studies on sexuality to discover if it is determined by genetics or environment. Using what you know about genetics and environment, draw your own conclusion about human sexuality: � Do you think people are born with a predisposition to be either straight or gay? � To what extent does peer influence have on sexuality? � How do cultural norms affect sexual behavior?