PSYCH 2AP3 Lecture Notes - Twin, Epigenome, Heritability
15 Jun 2013
School
Department
Course
Professor
Document Summary
Monozygotic (identical) twins: born from single fertilized egg. In terms of genetic activity, they are not identical. Share 100% of genes and 100% of gene effects. Dizygotic (non-identical) twins: can be of opposite sexes. On average the members of a dizygotic twin pair share 50% of genes. How do we use twins to study disorders: if any phenotypic character is completely dependent on genes then there is a 100% change that monozygotic twins will share this characteristic. If concordance rate is high, then we are confident in saying it is heavily genetic. If it is low we know there is an impact of experience on this character. We expect the same thing in dizygotic twins. Most mental disorders are relatively rare to find in monozygotic twins. Proportion of variability in phenotype accounted for by genetic not environmental variability in the population. Not about any single individual, it is a statement about group variability.
