“The key issue here is that the authors have searched through the entire genome to identify some difference between discordant twins. Given the number of tests, it is likely that some regions will show up as differentiated by chance. Without validation of the result in an independent data set it is not really possible to know whether there is any substance in this claim.”
Prof Gil McVean, Professor of Statistical Genetics, University of Oxford
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“The authors of this abstract utilized a very small number of samples and discovered certain epigenetic markers could be associated with sexual orientation. However, I am not sure whether ‘the predictive model’ as claimed in the abstract is a correct term given the overall sample size. At best the authors could only claim the potential association, but not predicting power.
“It is unclear what tissues they used for epigenetic profiling. Blood DNA is likely the source, which could be the caveat of this study. It has been continuously debated whether the methylation status of blood DNA could be used as epigenetic biomarker for brain-related phenotypes. In addition, additional cytosine modifications have been discovered in recent years and the experimental system used in this study could not distinguish some of these modifications. The interpretation of their results could be limited.
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