genetic inheritance Flashcards
what is genetic inheritance?
Genetic inheritance is the theory that abnormal behavior, in this case, depression, can be passed down through genes.
what are twin studies?
Twin studies are used based on the assumption that they share the same environment, therefore any change in their behavior must be attributed to their genetic differences
what are the two types of twins?
Monozygotic twins (MZ): Also called identical twins; they develop from one fertilized egg, which splits and forms two embryos.
Dizygotic twins (DZ): Also called fraternal twins; they develop from two different fertilized egg
what are concordance rates?
the probability that the same trait will be present in both members of a pair of twins.
what is the assumption made when studying twins?
if the concordance rate for MZ twins is significantly higher than for DZ twins or siblings, it is likely that there is a genetic component to the behavior. If the concordance rate is high for both MZ and DZ twins it may be assumed that environmental factors play a large role in the observed behavior.
what are three limitations of twin research?
Equal environment fallacy: the mistaken notion that twins share exactly the same environment. Environmental factors cannot be eliminated in twin studies. They often share the same experiences, regardless of whether they are MZ or DZ twins.
Twins are only a small number in the overall population. This leads to low population validity.
No specific gene is identified.
what are family studies?
In family studies, these different degrees of genetic relatedness are compared with respect to specific traits or behavior.
what are family studies also known as?
kinship
what is the assumption made in family studies?
The higher the genetic relatedness, the higher the probability that the behavior will be inherited. The notion is that concordance rates will increase if heritability is high and vice versa
what are two strengths of family studies?
more controlled than studies with unrelated people
more representative than twin studies
what are two limitations of family studies?
assumptions are made about past generations and their potential diagnoses
self reported data
what is on twin study?
kendler et al (2006)
what is the aim of Kendler?
to determine the role that genetics plays in major depressive disorder (MDD).
what were the results of Kendler?
Sex and Zygosity Concordance Rate (CR)
Female, MZ 44%
Female, DZ 16%
Male, MZ 31%
Male, DZ 11%
The results indicate that the concordance rates for major depression were significantly higher in women than men. In addition, the correlations were significantly higher in monozygotic than in dizygotic twins.
what are 4 limitations of Kendler?
correlational, no cause and effect
self reported data
no official diagnoses
informed consent
