behaviour Genetics
Behavior genetics is the school of thought that focuses on how much our genes and our
environment influence our individual differences
Genes
Genes are the biochemical units of heredity that make up chromosomes
• The influence of nature consists of the genes passed along by your parents the moment you were conceived.
Chromosomes
Chromosomes are threadlike structures made of DNA molecules that contain genes
• 46 chromosomes in each cell
• 23 received from each parent
DNA (deoxyribonucleic acid)
Is a complex molecule containing the genetic information that make up chromosomes
• The smaller sections of DNA strands, the stairs on a DNA’s staircase, store your genetic code, (your genes)
Genes
Genes are distinguished from one another by four-letter codes.
Each letter in the code (A, T, C, or G) is called a nucleotide
FACTS:
After mapping the human genome, they learned that humans have only about 25,000 genes (fruit fly has 15,000)
99.9% of your four-letter DNA sequences match that of every other human.
Mutations
are random errors in gene replications that lead to a change in the genetic code
Mutation is the source of all genetic diversity
• Some mutations are desirable
• Other mutations are undesirable and feared.
• like those that predispose someone to cancer
Presdisposition
merely means that the possibility of something happening through the genetic coding
predispositions are passed through DNA to future generations, creating the polential for
something to happen
• The environment may or may not trigger the predisposition (poor diet, polluted air, stress could lead to the predisposition to be a reality).
Environment
Environment is every non - genetic influence, from prenatal nutrition to the people and things
• Any influence, other than genetic, on an individual’s behavior
Includes:
• Prenatal environment
• The culture someone is raised in
• One’s family
- Socioeconomic group
Nature VS Nuture
Nature side entails the genetic code passed from parents to child
• Nurture side involves all environmental influences from prenatal development onward
• Which parts of human behavior can we attribute nature which can be attributed to nurture and which both?
Identical twins
are twins who develop from a Single fertilized egg that splits in two, creating two genetically identical organisms
Called monozygotic twins
• Must be of the Same sex
Fraternal twins
Fraternal twins are twins who develop from two different fertilized egg.
• They are genetically no more similar that any other two siblings, but they share a fetal environment
• Called dizygotic twins
• Can be different sexes
Heritability
is the degree to which traits
are inherited
• The proportion of an individual’s characteristics that can be attributed to genetics heritability
Twin studies
Twin studies are used to determine the heritability of a given trait
• Data is collected from both the identical twins and fraternal on a trait (raised in the same home)
• The data from each group is compared
Results of some studies:
researchers have found a greater similarity in intelligence among identical twins when compared to fraternal twins.
• Genetic influences on personalitity traits appear to follow the same pattern.
• if one identical twin is outgoing, the other identical twin is likely to be outgoing— more so than in the case of fraternal twins.
• Identical twins are unique in that they share 100% of the same genes, but, while they share the same genotype, they have slightly different phenotspes
• Some identical twins are mirror
images of each other (one being left-handed, the other right-handed; one having a mole on the left side of the face, the other having one on the right, etc.).
• Some identical twins may have different personalities and interests, showing that heritability of a trait does NOT mean it will occur, even in two people who share the same genes.
Adoptive studies
Here the biological parents are providing the nature, and the adoptive parents are providing the nurture.
•Compare adopted children’s traits with those of their biological parents and their adopted parents
• Trait similarities with biological parents are attributed to heredity (nature)
• Trait similarities with adopted parents are attributed to the environment (nurture)
Early brain developement
For our brains to meet their developmental potential, early experience is critical.
*. A child raised in abusive isolation will never learn to read, write, or speak like a normal adult.
• As you get older, your brain’s tissue will continue to change the brains pathways maintained through practice or experience will remain strong, negelcted pathways will fade with disuse.
( neurological pruning )
Peer influences
Peer influence in adolescence is very powerful
Many studies suggest a peer group is correlated with:
• school preformance
• smoking
• for learning cooperation
• for inventing new styles of interaction among people of the same age.
Parental influence
is important in the areas of:
• Education
• Discipline
• Responsibility
• Orderliness
• Charitableness
• Ways of interacting with authority figures
With genetic influences accounting for roughly half the variation in our personality traits,
parenting is a likely source to turn toward in accounting for the other half of those traits
Culture influence
culture includes the shared attitudes beliefs behaviours, norms, of a group communicated from one generation to the next
• Culture influences our food selection, religious choices, family activities, and more.
• We tend to believe that our culture’s way of raising children is the best way.
• Be careful with this belief: Successful child rearing has been accomplished using many methods
Culture
Culture includes the shared attitudes, beliefs, norms, and behaviors of a group communicated from one generation to the next
• The rules are passed down
• The “software of our minds”
• Different from nationality, race, and ethnicity
Culture VS Nationality
Nationality is NOT culture.
• Many nations have multiple, equally important, coexisting cultures.
• To say that your nation is your culture is to ignore the multiple cultures in a nation.
Race VS Culture
Race is NOT culture either.
• First, two people of the same race can be either different or simular culturally.
• Second, your race is a set of characterization (such as the amount of pigment in skin) programmed into your genetic code.
• Your culture is a set of behaviours and beliefs in you learn from the people in your environment
Individualism
giving priority to personal goals over group goals
• defining identity in terms of personal attributes rather than group identification
• In an individualistic society, a personal achievement like winning a spelling bee is seen as something for the individual winner to savour.
Collectivism
giving priority to the goals of the grow, personal identity accordingly
- (often the extended family or work group) &defining personal identity accordingly
• In a collectivist society, a personal achievement is seen as more of a reflection teachers (and family) or a win for the school
