quirk
n.a strange or unusual habit or part of someone's personality. It is usually something small that makes a person different from others but is not necessarily bad.
n.a peculiar behavioral habit or an unexpected aspect of something's character. Often implies a minor, idiosyncratic trait that is harmless or even endearing.
“One of his quirks is that he only drinks tea from a blue mug.”
“The old house has several quirks, like a kitchen floor that slopes slightly to the left.”
“While her writing style is generally formal, she occasionally indulges in the quirk of using archaic vocabulary to add a touch of historical flavor to her essays.”
Often used with the preposition 'of' to describe a specific habit.
“Have you noticed these or any other cultural quirks Spaniards have?”