Genetic Similarity terminology

Genetic Similarity terminology

Twin Study

• Use to compare concordance rates for behaviors of MZ with DZ to establish the extent of the genetic component of the behavior

• They feel they can do this as all participants MZ and DZ share the same environment. Hence any differences we see could be attributed to genetics.

Monozygotic

Single egg is fertilized then splits into two separate embryos which then implant into the uterus. Share identical DNA at birth because they were originally the same egg.

Dizygotic

• Two eggs are fertilized separately. These two separate gametes differentiate into two separate fetuses that mature into fraternal twins.

Concordance rate

Used to describe the rate of probability that two people with shared genes will develop the same behavior. (but also related to environment)   Identical (MZ) = 50% Fraternal (DZ) = 15%

Equal environment fallacy (CT)

Assumption that MZ and DZ share similar environments

• MZ and DZ are treated quite differently by parents, teachers, friends etc

• Can’t assume MZ and DZ share the same environment

Family study

Study of family history and genealogy as a means of tracing traits that might be inherited

Prospective study

Select and observe a family before certain behaviors are observed (researchers watch for outcomes)

Genetic vulnerability

• When considered genetically vulnerable to depression - be followed for many years to see if they actually develop the disorder

• Ethical concern

Research may cause undue stress in those who are labeled as vulnerable - producing self-fulfilling prophecy