What does Boxing Day have to do with boxing?
early 15c., "manner of carrying the body," from Medieval Latin gestura "bearing, behavior," from Latin gestus "gesture, carriage, posture" (see gest). Restricted sense of "a movement of the body or a part of it" is from 1550s; figurative sense of "action undertaken in good will to express feeling" is from 1916.
1540s, from gesture (n.). Related: Gestured; gesturing.