genetics study of how characteristics are pass along through
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GENETICS
• Study of how characteristics are pass along through inheritance.
• Genome– Inside each cell, the master blueprint
• Chromosomes– Structures within the cell made up of genes– 23 pairs– Have of each pair coming from each parent
• Genes– The basic units of heredity– DNA (deoxyribonucleic acid)
• Double helix – two intertwined strands of molecules of sugar, phosphate, and nitrogen.
– Sequence of these molecules represent instructions on how to build certain proteins
– Segment of DNA, a blueprint for making a certain protein.
• Gregor Mendal (1823-1884)– Selective breeding – pea plants
• Alleles– Two versions of a gene– Dominant gene
• Expressed in offspring whenever present
– Recessive gene• Expressed only when it is matched with a similar
gene from the other parent
• Genotype– Actual genetic makeup determined at time of
conception
• Phenotype– Observable physical characteristics of an
organism due to genes and environment
• Polygenic– Characteristics influenced by more than one
gene
•Why are you so different than your siblings?
• Behavioral genetics– How genes and environment interact to influence
behavior
• Twin studies– Monozygotic twins (identical twins)
• Same genes
– Dizygotic twins (fraternal twins)• Same wombmates but dissimilar genes
• Adoption studies• Identical twins raised together or raised apart
• Heritability– Variations among a population (differences in certain traits, eg.
height) ascribed (due to) genes or heredity. – Represented by a number from 1 to 0.– For example, if for a given population the characteristic of height
is given a score of .60, then 60% of all of the height differences is due to genes.
• Tongue curling– 1.0
• Language differences– 0
– The number is called a heritability coefficient• Genetic variance/total variance
– Must take the environment into serious consideration
DEVELOPMENT OF SEX AND GENDER
• Genetic sex– XX or XY
• Morphological (structural)– Differing genitals, internal as well as external
• Gender role– Behavior patterns that a given culture deems
appropriate for each sex
• Gender identity– Inner sense that we are male or female
• GENDER ROLES– What are some expected behavior for men
and women in our culture?– “gender belief system” – Parents treat their children differently– Play with “Joey” or “Janie”– Violations by children are frowned upon
• SEX DIFFERENCES IN GENDER ROLES– Physical differences– Maturity differences– Brain differences
• Aggression– Males are more active and physically
assertive than females• Even in utero• Continues into adulthood• Cross cultural• Nature predisposes boys and nurture magnifies it.
– Girls are still aggressive, but less physically• Relational aggression
– Altering social alliances– Why?
• Patterns of Intellectual Aptitudes– Boys and men do better on spatial and math– Girls do better on many verbal tasks
• Top 10% kids
– Nature or nurture?• Some credence to suggest nurture but• Brain differences in regions of verbal and
visuospatial task. What accounts for this?
• Testosterone and spatial abilities– Low levels of testosterone show impairment in
visuospatial skills• Old men
– Effects girls too!• Adrenal tumors• Menstrual cycle
• Culture and Cognitive Abilities– Cultural expectations– Internalized by women
• Test results
• Gender Identity– By age three, most kids can report who is
male and female and identify their own sex but…
– Four year olds– Preschoolers determine sex by hair length
more than genitals– Gender constancy
• Intersexuality and sex reassignment– Intersexuals
• Children who are clearly not either male or female• 2% of live births• True hermphroditism
– Functioning reproductive tissue from both sexes
• Pseudohermaphroditism– One in two-thousand births
– External genitals, sometimes internal, anatomically ambiguous
• Ambiguous genitalia and sex reassignment– Five a year in the United States
– “When in doubt, make it a female.”
• The Effects of Reassignment– The case of “John”– Biological factors can have an influence
• Androgenized girls
• Guevedoces Syndrome– Rare genetic disorder in three rural villages of
the Dominican republic– During fetal stage unaffected by androgens
GENDER ROLE DEVELOPMENT THEORIES
• Social learning theory
• Gender schema theory
SOCIAL LEARNING THEORY
• People learn behaviors mainly through observation and mental processing of information
• Parents and newborn children
• Role of peers
GENDER SCHEMA THEORY
• Combines aspects of social learning theory and the cognitive perspective
• Cognitive structures that assimilate and organize information about women and men.– Gender schematic– Gender aschematic– Gender schemas develop early