Chapter 3 Biology and behavior
Nature and nurture
Genome = complete set of genes of any organism
1. Genotype = genetic material an individual inherits
2. Phenotype = observable expression of genotype, including body
characteristics and behavior
3. Environment
These three elements are involved in 5 relations important in the development of
every child:
1) parents’ genetic contribution to the child’s genotype
a) Chromosomes with DNA (deoxyribonucleic acid).
b) Genes are codes for production of certain proteins.
c) XX = female, XY = male → father determines the sex.
d) Mutation = a change in a section of DNA → increase resistance to
disease/adapt to environment → evolution
e) Crossing over = process by which sections of DNA switch from one
chromosome to the other → promotes variability
2) contribution of the child’s genotype to his/her own phenotype
a) Endophenotypes = intermediate phenotypes including brain &
nervous systems that do not involve overt behavior
b) Genes are turned on and off → regulated by regulator genes.
c) Genes never function in isolation: one turned off, other turned on, etc.
d) Dominant vs. recessive alleles → homozygous or heterozygous for trait
e) Males are more likely to suffer from sex-linked inherited disorders
because of recessive alleles on their chromosomes.
f) Polygenic inheritance = inheritance in which traits are governed by
more than one gene.
3) contribution of the child’s environment to his/her phenotype
a) Norm of reaction = all the phenotypes that can theoretically result
from a given genotype in relation to all the environments in which it can
survive and develop.
b) PKU = a disorder related to a defective recessive gene on
chromosome 12 that prevents metabolism of the amino acid
phenylalanine.
c) Parent’s relationship with child is important part of the environment →
is genetically influenced.
4) influence of the child’s phenotype on his/her environment
a) Child as source of own development → active creators of environment:
i) actively evoke certain kinds of responses from others
ii) actively select surroundings and experiences that match their
interests, talents, and personality characteristics.
Nature and nurture
Genome = complete set of genes of any organism
1. Genotype = genetic material an individual inherits
2. Phenotype = observable expression of genotype, including body
characteristics and behavior
3. Environment
These three elements are involved in 5 relations important in the development of
every child:
1) parents’ genetic contribution to the child’s genotype
a) Chromosomes with DNA (deoxyribonucleic acid).
b) Genes are codes for production of certain proteins.
c) XX = female, XY = male → father determines the sex.
d) Mutation = a change in a section of DNA → increase resistance to
disease/adapt to environment → evolution
e) Crossing over = process by which sections of DNA switch from one
chromosome to the other → promotes variability
2) contribution of the child’s genotype to his/her own phenotype
a) Endophenotypes = intermediate phenotypes including brain &
nervous systems that do not involve overt behavior
b) Genes are turned on and off → regulated by regulator genes.
c) Genes never function in isolation: one turned off, other turned on, etc.
d) Dominant vs. recessive alleles → homozygous or heterozygous for trait
e) Males are more likely to suffer from sex-linked inherited disorders
because of recessive alleles on their chromosomes.
f) Polygenic inheritance = inheritance in which traits are governed by
more than one gene.
3) contribution of the child’s environment to his/her phenotype
a) Norm of reaction = all the phenotypes that can theoretically result
from a given genotype in relation to all the environments in which it can
survive and develop.
b) PKU = a disorder related to a defective recessive gene on
chromosome 12 that prevents metabolism of the amino acid
phenylalanine.
c) Parent’s relationship with child is important part of the environment →
is genetically influenced.
4) influence of the child’s phenotype on his/her environment
a) Child as source of own development → active creators of environment:
i) actively evoke certain kinds of responses from others
ii) actively select surroundings and experiences that match their
interests, talents, and personality characteristics.
