Epigenetics is the scientific study of how a living thing’s experiences can change the way its genes behave — without changing the DNA letters themselves. Think of genes as a recipe book. Epigenetics is more like sticky notes on the recipes: “use this one a lot,” “leave this one shut.” Food, stress, smoke, and even how warm a place is can add or take off those marks. Some marks can be passed to children, though not as simply as a hair-colour gene. You will meet the word in biology and health news, not in the market. Though actually, the word is younger than it sounds. C. H. Waddington coined it in 1942 by blending epigenesis (how a body grows and takes shape from one cell) and genetics. His idea was about development. Today’s usual meaning has shifted toward those chemical sticky notes on DNA. When a headline says “this food changes your DNA,” it is usually stretching; more honestly, it may change how your DNA is read.