Genetics and Psychology How much do genes decide our behavior? Pages 72-74.

Genetics and PsychologyHow much do genes decide our behavior?

Pages 72-74

Genes: Our Code for life

Ms. Martin shares 98% with

And 99.9% with

All cells contain DNA

Chromosomes and Genes Each cell has 46 chromosomes = 23

pairs Genes give instructions to perform a

certain function Two of this set are X and Y (the sex

chromosomes) and the other 22 pairs guide the expression of other traits.

Dominant vs Recessive genes 2 recessive genes

= recessive trait 1 dominant + 1

recessive = dominant

2 dominant = dominant

Behavior Geneticists Ask questions about

the extent that genetics plays on our differences

Heritability – statistical estimate of how much behavior is due to genes. Max value is 1.0

Twin Studies Identical Twins- develop

from a single fertilized egg that splits in two, creating two genetically identical organisms

Fraternal Twins - develop from separate eggs genetically no closer

than brothers and sisters, but they share the fetal environment

Twins and heritability studies Bouchard – studied

100 twins raised apart and their IQ scores

Those raised apart = coefficient of .69 on IQ test Those raised together

= .88 Criticized = adopted

parents have particular environment

Molecular Genetics Looks at genes that

can specifically cause disorders

Gender determined by 23rd chromosome pair Men = XY – means

some recessive characteristics from mother not blocked (color blindness)

Women = XX

Chromosomal Disorders Turner’s Syndrome

Single X on 23rd pair

Shortness, webbed necks, sterility

Chromosomal Disorders Klinefelter’s

syndrome – XXY pattern Males – less

testosterone, weaker body, possible infertility

Down’s Syndrome Extra

chromosome on the 21st pair

Geneticists can now test for some disorders in Utero Down’s syndrome Tay-Sachs disease (death to nerve cells

mental/physical deform. onset 6mo.-death @4)

Spina Bifida (one of most common in U.S. 1/1000 births – spinal)

Looking for an increase in a protein or hormone in early pregnancy