For how we live.
Low testosterone is a symptom, not a diagnosis. It splits into testicular and pituitary causes — and Klinefelter syndrome, the commonest genetic cause, is found in only about a quarter of the men who have it.
Very long life carries real genetic signals — the APOE gene most robustly, FOXO3 in some populations. But pedigree studies put the true heritability of human lifespan well below 10%.
From LA28, every entrant in an Olympic female-category event is screened for one Y-chromosome gene. Geneticists, including the man who found it, say the test answers a narrower question than the policy asks.
Whole-genome sequencing of 78 families put the figure at two mutations per year of paternal age. A cohort of 40 million US births found small increases in preterm birth and gestational diabetes.
An inactive enzyme carried by an estimated 540 million people lets a carcinogen build up when they drink. In heavy-drinking carriers, oesophageal cancer risk runs many times higher.
A meta-analysis of 27 randomised trials found that disclosing a polygenic risk score did not meaningfully shift diet, screening uptake, medication use, anxiety or cholesterol.
Carriers of loss-of-function MC4R mutations had lower LDL and triglycerides than UK Biobank controls of similar adiposity, and lower cardiovascular risk. The brain sets body weight and lipids separately.