The purpose of this assignment was to find a genetics-related primary article from a peer-reviewed journal and write a summary of that article.

The article titled “Shared genetic and environmental influences on early temperament and preschool psychiatric disorders in Hispanic twins” starts by introducing that even though psychiatric disorders can be diagnosed early on, there is still little information about how soon genetic and environmental factors can influence these developed disorders. 

The method of this study was to assess Hispanic twins with infant temperament at age 1 and in ages 3 to 5, attention deficit hyperactivity disorder (ADHD), separation anxiety disorder (SAD), and opposition defiant disorder). The researchers estimated genetic, shared, as well as non-shared environmental effects for each of the psychiatric disorders and the temperament construct using a statistical program. Genetic models with multiple variables were fitted to be able to identify if different or the same sets of genes and environmental effects show a link between this early temperament and psychiatric disorders around the preschool age. 

As a result of these tests, 61% of the identified variance in ADHD, 21% in ODD, and 28% in SAD was based on genetics. 34% was the variance in ODD and 15% of SAD through environmental factors. These results show that difficult infant temperament issues were in some way associated with ADHD, SAD, and ODD at preschool age. Both environmental factors and genetic factors lead to as association between SAD and ODD. 

Silberg, J. L. et al. Shared genetic and environmental influences on early temperament and
preschool psychiatric disorders in Hispanic twins. Twin research and human genetics: the
official journal of the International Society for Twin Studies.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4402136/. (2015)