1. Presented by Alicia Naegle Twin Studies

2. Important Vocabulary Monozygotic Twins (MZ)- who are identical twins Dizygotic Twins (DZ)- who are twins that do not look alike, also called fraternal Concordance- means two twins share a phenotype [visible trait] Discordance- means they do not share that particular trait [concordance is used to estimate heritability] Heritability measures the fraction of phenotype variability that can be attributed to genetic variation.

3. Types of twin studies 1.Classical twin studies -compares MZ and DZ twins, focusing on phenotypic alikeness or differences. This study takes in to account the environmental factor for twins reared together, or raised apart. Classical twin studies also tests for age and sex differences(Boomsma).

4. 2.Multivariate Analysis-The name tells exactly what this study does, it examines many variables at once. An extended twin study is where the focus of the study is more on the family as a whole, taking account of external environment as well as the internal or prenatal environment (Wray).

5. 3.Co-twin control studies- involve "case-control studies of MZ twins who are perfectly matched for genes and family background” (Nature.com). - Measures genotypes in discordant twins 4. In Genotyping at a candidate loci, MZ twins’ genotypes are studied to determine genetic variability, and DZ twins’ genotypes are studied to find the connection of those genes within the family (Wray).

6. 5.Genotyping at a marker loci- uses DZ twins’ genotypes and compares them to their parent’s genotypes to study a chosen marker loci (which is part of a chromosome used to identify links between parent and child) to find the QTL, which is the quantitative trait loci (Boomsma).

7. Twin registers These aid in the organization of twin studies. The administrators of most of the registers maintain contact with the twins and their family members by sending out newsletters and through mailed surveys. There is also a way to collect updated samples of DNA through the mail. The phenotypes that are stored in these registers include many traits whether they are behavioral or clinical (Boomsma).

9. Twin studies of Schizophrenia “Schizophrenia as a Complex trait” - This study used meta-analysis on twelve separate twin studies to analyze against each other to be sure the results were unbiased. Meta- analysis is where the hypothesis of several related studies are compared to one another.

10. Twin studies and Psychopathology ” Genetics and Developmental Psychopathology”- a study in Virginia of adolescent Caucasian twins to find out more about the risk for juvenile psychopathic disorders with the factors of genes, and the environment. consisted of 1412 twin pairs ages 8-16. Interviews conducted with an evaluation called CAPA. (Child and Adolescent Assessment) Made standardized rating to compare all results to after the CAPA data was in.

11. Twin studies of SLE’s/Depression “Stressful Life Events and Depression among Adolescent Twin Pairs” – looked to see if SLEs had to do with genetics. It is. 37% of the variety of depression found in teens is due to genetics (Boardman). Independent, as well as dependent stressful life events and depressive traits were considered for this analysis.

12. Importance of Twin Studies Twin studies are helpful in determining where disorders originate. Examining the traits in identical and non-identical twins is helpful to see that genes are affecting which traits Studying the influence of genes in medical conditions and disorders, we can hopefully help “fix” the problems. We get to take a look at the relation to behaviors and genetics Gene studies show the relation to genetic inheritability and we can see by studying twins’ genes that some diseases and disorders may not be genetic. Twin studies are definitely helpful for diving into our genetics and solving the mystery of nature vs. nurture.