Mendelian randomization (MR; for the interested layman - the term for instrumental variables techniques when the instrument is genotype) is a well-founded resea

Mendelian randomization (MR; for the interested layman - the term for instrumental variables techniques when the instrument is genotype) is a well-founded research paradigm with several known potential flaws which I discussed in more depth in reply to another comment below. But, fundamentally I agree with your assessment that the study does not definitively answer the question. More generally, the articles I referenced in the other comment may be of interest to you as well - specifically around the reliability of MR studies in general. [1] doi:10.1038/s41588-018-0099-7 [2] doi:10.1093/hmg/ddy163