“How Children Develop”
Sixth edition:2020: Robert S. Siegler; Jenny Saffran; Nancy Eisenberg; Elizabeth Gershoff
Chapter 3 – Biology and behavior
Nature and nurture
Summary:
The starting point for development is the genotype - the genes inherited at
conceptions from the parents. Only some of the genes are expressed in the
phenotype, one observable characteristics. Whether some genes are expressed at
all is a function of dominance patterns. Most traits studied by developmental
scientists are influenced by multiple genes
The eventual outcome of a given genotype is always contingent on the
environment in which it develops. Parents and their behavior toward their
children - which is influenced by the parents own genotypes - are a salient part if
the children's environment. Similarly, the child's development is influenced by the
aspects of environment he or she seeks out and the different responses the
child's characteristics and behavior evoke from other people
Epigenetic effects - the switching on and off genes - underlies many aspects of
development and individual differences. This process is affected by experience via
methylation
History of gene science and understanding
From long before the understanding of hereditary, people knew that traits "ran in
families"
o Selective breeding
Gregor Mendel
o Pees - green and yellow
1950s: James Watson, Francis Crick and Rosalind Franklin
o Structure of DNA
Recent years
o Mapping of he entire genome
o Gene synthesis
Genetic and environmental forces
Genotype: inherited genetic material
Phenotype: observable characteristics and expression of the genome
Environment: every aspect og individuals and their surroundings other than the
genes themselves
1. Parents´ genotype-child´s genotype
Genetic material from parents to child
Chromosomes consisting of two long strands of DNA
Genes are segments of DNA that is a code for a protein
Human hereditary
o 46 chromosomes - 23 pairs
o Genes of the same type on the locus on each chromosome pair
Genetical diversity and individual differences
o Random assortment to assure variability
, o Crossing over: when gametes divide, two members of a pair of chromosomes
sometimes swap sections of DNA
o Mutation: some are random, other caused by environmental causes
Can be passed onto an offspring
Basis of evolution
Sex determination
o Genetic females have two identical, large X chromosomes
o Genetic males have on X and one Y
o The genetic male partner always decides on the offspring's gender
2. Child´s genotype - child´s phenotype
Endophenotypes: unobservable, intermediate aspect of the genome, our brain and
nervous system
Some genes turn on, and some don´t
Gene expression: Developmental changes
o The difference between the genotype and phenotype
o The switching on and off genes is controlled by regulator genes
o The activation of a turned off gene is a part of a chain of genetic events
o Genes never function in isolation
o A given gene can function multiple times in multiple places during
development
o External factors can also turn on and off gene
Thalidomide on limb development
Early visual experience is important for the visual system as it turns on
some genes, which in turn turns off other genes
o Gene expression: Dominance patterns
Alleles in a gene influence the same trait of characteristics
Dominant-recessive pattern: dominant and recessive genes
Two of the same allele (homozygot)
Two of the different alleles (heterozygot)
Inheritance patterns are very complicated
3. The child´s environment - child´s phenotype
PKU: a disorder related to a defective recessive gene of chromosome 12
Abusive parenting and effects on the interaction with the child´s genotype to
produce different adult outcomes
o MAOA genes, an X-linked gene
Parental contributions to the child´s environment
o Parents are central through their interactions with the offspring
o Parents behavior towards their children is genetically influenced
o This has been tested a lot
4. Child´s phenotype - Child´s environment
Active child theme: children are a source of their own development
Children experience different environments because of their behavior and
personality, despite living in the same house
Sixth edition:2020: Robert S. Siegler; Jenny Saffran; Nancy Eisenberg; Elizabeth Gershoff
Chapter 3 – Biology and behavior
Nature and nurture
Summary:
The starting point for development is the genotype - the genes inherited at
conceptions from the parents. Only some of the genes are expressed in the
phenotype, one observable characteristics. Whether some genes are expressed at
all is a function of dominance patterns. Most traits studied by developmental
scientists are influenced by multiple genes
The eventual outcome of a given genotype is always contingent on the
environment in which it develops. Parents and their behavior toward their
children - which is influenced by the parents own genotypes - are a salient part if
the children's environment. Similarly, the child's development is influenced by the
aspects of environment he or she seeks out and the different responses the
child's characteristics and behavior evoke from other people
Epigenetic effects - the switching on and off genes - underlies many aspects of
development and individual differences. This process is affected by experience via
methylation
History of gene science and understanding
From long before the understanding of hereditary, people knew that traits "ran in
families"
o Selective breeding
Gregor Mendel
o Pees - green and yellow
1950s: James Watson, Francis Crick and Rosalind Franklin
o Structure of DNA
Recent years
o Mapping of he entire genome
o Gene synthesis
Genetic and environmental forces
Genotype: inherited genetic material
Phenotype: observable characteristics and expression of the genome
Environment: every aspect og individuals and their surroundings other than the
genes themselves
1. Parents´ genotype-child´s genotype
Genetic material from parents to child
Chromosomes consisting of two long strands of DNA
Genes are segments of DNA that is a code for a protein
Human hereditary
o 46 chromosomes - 23 pairs
o Genes of the same type on the locus on each chromosome pair
Genetical diversity and individual differences
o Random assortment to assure variability
, o Crossing over: when gametes divide, two members of a pair of chromosomes
sometimes swap sections of DNA
o Mutation: some are random, other caused by environmental causes
Can be passed onto an offspring
Basis of evolution
Sex determination
o Genetic females have two identical, large X chromosomes
o Genetic males have on X and one Y
o The genetic male partner always decides on the offspring's gender
2. Child´s genotype - child´s phenotype
Endophenotypes: unobservable, intermediate aspect of the genome, our brain and
nervous system
Some genes turn on, and some don´t
Gene expression: Developmental changes
o The difference between the genotype and phenotype
o The switching on and off genes is controlled by regulator genes
o The activation of a turned off gene is a part of a chain of genetic events
o Genes never function in isolation
o A given gene can function multiple times in multiple places during
development
o External factors can also turn on and off gene
Thalidomide on limb development
Early visual experience is important for the visual system as it turns on
some genes, which in turn turns off other genes
o Gene expression: Dominance patterns
Alleles in a gene influence the same trait of characteristics
Dominant-recessive pattern: dominant and recessive genes
Two of the same allele (homozygot)
Two of the different alleles (heterozygot)
Inheritance patterns are very complicated
3. The child´s environment - child´s phenotype
PKU: a disorder related to a defective recessive gene of chromosome 12
Abusive parenting and effects on the interaction with the child´s genotype to
produce different adult outcomes
o MAOA genes, an X-linked gene
Parental contributions to the child´s environment
o Parents are central through their interactions with the offspring
o Parents behavior towards their children is genetically influenced
o This has been tested a lot
4. Child´s phenotype - Child´s environment
Active child theme: children are a source of their own development
Children experience different environments because of their behavior and
personality, despite living in the same house
