性せい癖へき

癖くせN3sense 1
癖 is a general habit or mannerism, often trivial or physical, while 性癖 points to a deeper, more ingrained (and sometimes odd or sexual) disposition.
性せい的てき嗜し好こう sense 2
性的嗜好 is the neutral, clinical term for sexual preference, while 性癖 in this sense is a more colloquial, often self-deprecating word for a fetish.
傾けい向こうN3sense 1
傾向 is a neutral word for a general trend or tendency, whereas 性癖 usually implies a personal, somewhat peculiar trait.
フェチ sense 2
フェチ is a casual loanword for a specific fetish object or focus, while 性癖 more broadly covers one's whole sexual inclination.
習しゅう性せい sense 1
習性 refers to an instinctive or ingrained habit (often used for animals as well as people), while 性癖 stresses a personal quirk that can seem odd.

Don't confuse with

潔けっ癖ぺき
潔癖 shares the kanji 癖 with 性癖 but means an obsessive fastidiousness about cleanliness or morals, not a personal inclination or fetish.
習しゅう性せい
性癖 refers to a personal proclivity or inclination (sometimes with a negative or sexual connotation), whereas 習性 describes a general behavioral trait or habit, especially of animals.

Compound of 性 (nature, character) and 癖 (habit, mannerism). The combination naturally yields the sense of an ingrained personal tendency.