Genetics and Psychology How much do genes decide our behavior? Pages 72-74
Apr 01, 2015
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