Fortunately they can be overcomeif the 2 kind of

Fortunately, they can be overcome…If the 2 kind of studies produce
similar results on the influence of heredity, we can be confident of those results
4.
Polygenic inheritance has been examined more recently by isolating
particular segments of DNA which serves as a marker for identifying specific alleles
1.
Compare DNA markers between 2 groups that differ in the
behavior/psychological trait being studied; if different consistently = alleles near the
marker probably contribute to the differences b/w the groups

Genetic Bases of Child Development
Chapter 2
2.
Have the potential to identify the many diff. genes that contribute to
complex behavioral and psychological traits
3.
Limits
1.
Requires large samples
2.
Some require investigator have an idea before even beginning
to study about which chromosomes to search and where
5.
Which psychological characteristics are affected by heredity?
1.
Research reveals consistent genetic influence in many psychological areas
(personality, mental abilities, psychological disorders, attitudes, and interests
2.
Study looking at depression: Twin studies  MZ twins show remarkable
similarity (if 1 twin depressed, other has ~50% chance of being depressed as well);
for DZ twin’s percentage is much lower (~25%)
3.
Can also see the influence of heredity in cognitive development
1.
Study looking at heredity and environmental bases of aggressive behaviors
between twins 6 years of age (234 pairs of twins)
1.
Teachers/peers rated each twin on levels of social and physical aggression
2.
Results for physical aggression: highest correlation b/w MZ twins (twice as
highly correlated as same-sex DZ twins)
3.
Results for social aggression: roughly equal for all twin pair types
4.
Conclusion: Strong genetic component to physical aggression, but a more
environmental explanation for social aggression

envir./exposure to certain envir.
Factors must contribute/influence behavior; physical aggression tended to underlie
social aggression
5.
Converging evidence to strengthen proposed conclusion that aggression and
the diff. effects of diff. influences on aggression change over time = Conduct a
longitudinal study to see whether MZ and DZ twins’ aggressive behaviors would
become more or less alike as they grew
1.
PATHS FROM GENES TO BHEAVIOUR
6.
1) The behavioral consequences of genetic instructions depend on the
environment in which those instructions develop
1.
Reaction rages

same genotype can produce a range of phenotypes in
reaction to the envir. Where development takes place

Genetic Bases of Child Development
Chapter 2
1.
Ex: Child brought up in an impoverished non-stimulating envir. = Phenotypic
intelligence may be below avg. compared to an enriched envir. Filled with
stimulation = phenotypic intelligence may be above avg.