Tendency

Internal state such that a particular behaviour is likely to occur given an actor's exposure to a particular stimulus or situation, or that a particular trait is likely to spread in a population given it enhances (or does not inhibit) an organism's viability;

more generally: a disposition or natural inclination towards (something), a conduciveness to some action, behaviour, or result – likely to act in a particular way or likely for something to happen or happen often;

a shift towards a particular direction (of opinion, etc).

(see also: trend)