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