In epidemiology, Mendelian randomization is a method of using measured variation in genes of known function to examine the causal effect of a modifiable exposure on disease in non-experimental studies. The design was first described by Gray and Wheatley (1991) as a method for obtaining unbiased estimates of the effects of a putative causal variable without conducting a traditional randomised trial. These authors also coined the term Mendelian randomization.
Read more about Mendelian Randomization: Background: The Problem of Spurious Findings in Observational Epidemiology, The Mendelian Randomization Approach