a spontaneous or natural liking or sympathy for someone or something.
Merriam-Webster Online Dictionary
affinity (noun)1.
relationship by marriage
2.
a) sympathy marked by of interest - community kinship
b) (1) an attraction to or liking for something - people with an affinity to darkness Mark Twain pork and fennel have a natural affinity for each other Abby Mandel
(2) an force between substances or particles that causes them to enter into and remain in chemical combination - attractive
c) a person especially of the opposite sex having a particular attraction for one
3.
a) likeness based on relationship or causal connection - found an affinity between the teller of a tale and the craftsman Mary McCarthy this investigation, with affinities to a case history, a psychoanalysis, a detective story Oliver Sacks
b) a relation between biological groups involving resemblance in structural plan and indicating a common origin attraction