Polygenic Traits Rule

The traits people obsess over — height, intelligence, personality — are polygenic. That means each one is shaped by hundreds or thousands of genes, every one adding a tiny nudge. There is no single "tall gene." Thousands of variants each push your height up or down by a sliver, and your final height is the sum of all those small pushes.

Because so many genes share the work, predicting a trait from DNA alone is hard. Even a full genome reading can only place your likely height inside a fairly wide range, not pin an exact number. For traits like personality or behavior, genetic prediction is far rougher still. Genes set the odds; they do not write the script.