trait

A trait is a distinguishing feature of somebody's character. One of the things that makes them recognisable.

Psychology uses it technically, since trait theory describes personality as a set of stable measurable traits rather than as a type. Genetics uses it for an inherited feature, so eye colour is a trait. Everyday use is looser and usually slightly critical, since describing something as a family trait often means a family fault. The pronunciation drops the final t in British English, which surprises people who have only read it.