Lecture 6

Question 1

What is Quantitative genetics?

Answer 1

Quantitative genetics measures how much of the phenotypic differences among individuals are due to genetic and environmental influences. This is done predominantly on complex traits, and cannot specify genes or environmental factors.

Question 2

Discuss a Family Design.

Answer 2

Studies narrow sense heritability between individuals who are related / who share alleles that can be traced through descent.
+ Families share alleles, so it excludes necessary genetic variation. It also controls for some environmental influences.
- It’s difficult to find big families to study; and then to repeat the research.

Question 3

Discuss an Adoption Design.

Answer 3

Adoption design compares phenotypic resemblance between adoptee and biological vs adoptive parents.
+ Can see the extent of environmental influence (consider GEI)
- Can be traumatic and induce psychological abnormalities

Question 4

Discuss a Twin Design.

Answer 4

Monozygotic twins are 100% genetically identical. Dizygotic twins are 50% genetically identical. MZ twins are compared to each other (how often the two score the same); DZ twins are compared to each other (how often the two score the same); and then the concordance between MZ and DZ twins is estimated.
+ Can see the extent of the genetic influence (consider when MZ are similar and not, regardless of environment)
- Twins are not representative of the general population.
Equal environments assumption – assumes that twins experience more similar environments regardless of whether they are MZ or DZ.