Stress clearance, focus, mood, and the genes behind them.
Your body clears stress hormones at a genetically set speed, and the COMT and FKBP5 genes mean some people recover in hours while others take days.
Often yes - much of the classic 3pm fog traces to how your body absorbs B12 and iron and how deeply you sleep, all of which have a strong genetic component.
A gene called ADORA2A controls how sensitive your brain's receptors are to caffeine, so some people feel jittery and anxious on a dose that barely registers for others.
Stress-clearance genes set your baseline, but the context decides when you feel it - many slow-clearing people hold it together under structure and crash once the structure drops.