Peccadillo

Strictly speaking, a peccadillo is an indiscretion, a petty misdeed, or a minor sin. More recently, the use of the word has been extended to mean a flaw or a peculiarity.

The plural can be spelled with or without an e before the s.

"All butterflies have their little peccadilloes and one of the Peacock's is to land on pieces of white paper to sunbathe."