THEME 6
I. THE HUMAN GENOME 101
• genome = collection of genes that make up our DNA
• genes are located on chromosomes (pairs of one from mom, one from dad)
↳ recombination = randomization and mixing up chromosomes for each generation
o men have XY for the 23rd chromosome pair and women have XX
• genes are specific sequences of nucleotides, but only a small part of the genome has them
↳ different versions of a gene = alleles
• DNA = deoxyribonucleic acid
↳ 2 long strands with nucleotides (2 types of combos)
→ adenine (A) - thymine (T)
→ guanine (G) - cytosine (C)
!!! 2 important findings about the human genome:
o how the genes are decoded into proteins is more variable and complex than in
animals (for us humans)
o certain areas of chromosomes are darker → gene dense areas → 'urban center'
↳ initially thought lighter areas were functionless residue, but it turns out they
have a role: to provide structural integrity
II. CONTROVERSY OF GENES & PERSONALITY
, Behavioral genetics attempts to find the degree to which individual differences are caused by
gene and how they interact with the environment.
*Designer babies’ controversy, political agenda, eugenics
III. GOALS OF BEHAVIORAL GENETICS
Behavioral geneticists aim to determine to what extent an individual difference is caused by a
gene
* Ex: height is 90% genes and 10% environment, from nutrition, medical care
• percentage of variance = was the point of interest, but now geneticists are more
interested in finding how genes and the environment correlate with each other and where
in the environment the effects are taking
IV. WHAT IS HERITABILITY?
• heritability = what proportion of variance observed in group of people can be accounted
for by genetic variance
• phenotypic variance = the observed individual differences (height, weight, personality).
• genotypic variance = individual differences in the total collection of genes possessed by
each person
• environmentality = proportion of phenotypic variance that is not accountable by genetic
variance
!!! Misconceptions
• heritability is not applied to a single individual, it is applied to a group/ population
• heritability depends on both genetic variation in the population and environmental
differences
• heritability is not a precise statistic
Nature-Nurture Debate -clarified
It can't be alone at the level of the individuals; it's done at population level where differences
between genes and environment can be disentangled.
At population level you can partition the differences into 3 aspects: genes, environment and their
interactions.
V. QUANTITATIVE GENETIC METHODS
→ these methods usually try to estimate to what phenotypic variance covaries in families
1. SELECTIVE BREEDING - Studies of Humans' Best Friend
• artificial selection happens only when the specific desired trait is heritable
↳ selective breeding = identifying the dogs and having them mate with others which
have the same characteristic (usually physical traits, but behavioral are possible as well; ex.
aggression)
I. THE HUMAN GENOME 101
• genome = collection of genes that make up our DNA
• genes are located on chromosomes (pairs of one from mom, one from dad)
↳ recombination = randomization and mixing up chromosomes for each generation
o men have XY for the 23rd chromosome pair and women have XX
• genes are specific sequences of nucleotides, but only a small part of the genome has them
↳ different versions of a gene = alleles
• DNA = deoxyribonucleic acid
↳ 2 long strands with nucleotides (2 types of combos)
→ adenine (A) - thymine (T)
→ guanine (G) - cytosine (C)
!!! 2 important findings about the human genome:
o how the genes are decoded into proteins is more variable and complex than in
animals (for us humans)
o certain areas of chromosomes are darker → gene dense areas → 'urban center'
↳ initially thought lighter areas were functionless residue, but it turns out they
have a role: to provide structural integrity
II. CONTROVERSY OF GENES & PERSONALITY
, Behavioral genetics attempts to find the degree to which individual differences are caused by
gene and how they interact with the environment.
*Designer babies’ controversy, political agenda, eugenics
III. GOALS OF BEHAVIORAL GENETICS
Behavioral geneticists aim to determine to what extent an individual difference is caused by a
gene
* Ex: height is 90% genes and 10% environment, from nutrition, medical care
• percentage of variance = was the point of interest, but now geneticists are more
interested in finding how genes and the environment correlate with each other and where
in the environment the effects are taking
IV. WHAT IS HERITABILITY?
• heritability = what proportion of variance observed in group of people can be accounted
for by genetic variance
• phenotypic variance = the observed individual differences (height, weight, personality).
• genotypic variance = individual differences in the total collection of genes possessed by
each person
• environmentality = proportion of phenotypic variance that is not accountable by genetic
variance
!!! Misconceptions
• heritability is not applied to a single individual, it is applied to a group/ population
• heritability depends on both genetic variation in the population and environmental
differences
• heritability is not a precise statistic
Nature-Nurture Debate -clarified
It can't be alone at the level of the individuals; it's done at population level where differences
between genes and environment can be disentangled.
At population level you can partition the differences into 3 aspects: genes, environment and their
interactions.
V. QUANTITATIVE GENETIC METHODS
→ these methods usually try to estimate to what phenotypic variance covaries in families
1. SELECTIVE BREEDING - Studies of Humans' Best Friend
• artificial selection happens only when the specific desired trait is heritable
↳ selective breeding = identifying the dogs and having them mate with others which
have the same characteristic (usually physical traits, but behavioral are possible as well; ex.
aggression)
