Maimonides codifies the biblical prohibition of keeping gentile customs (Laws of Idolatry 11:1):
אין הולכין בחקות העובדי כוכבים ולא מדמין להן לא במלבוש ולא בשער וכיוצא בהן שנאמר ולא תלכו בחקות הגוים. ונאמר ובחקותיהם לא תלכו. ונאמר השמר לך פן תנקש אחריהם
We don't follow the mores of the idolators, nor do we imitate them, neither in dress or hairstyle, etc., for it says, "and go not in the mores of the gentiles," and it says, "and in their mores go not", and it says, "guard yourself lest you stumble after them".
This idea perhaps exemplifies the underlying ideological battle between the Maccabees and the Mithyavnim (Hellenized Jews). Hellenism believed in a religious "pluralism" antithetical to the Jewish claim of one G-d, and persecuted the Jews for their religious chauvinism (see Maharal, Ner Mitzvah).
Nonetheless, after close to two millennia exiled among the nations, it is perhaps no surprise that many customs appear to have infiltrated into the Jewish mimetic tradition. Perhaps this is most marked with regard to the festive practices associated with the pagan-to-Christian holidays, particularly Saturnalia/Christmas.
Ironically, among these practices appear to be the (perhaps commercially-initiated) sending of Chanuka cards, giving of Chanuka presents, giving of foil-wrapped chocolate "gelt" to children, and gambling, particularly with dreidels. (To my knowledge, Chanuka bushes have not infiltrated yet into the more traditional Jewish communities.)
Do any rabbinic authorities discuss (in writing or orally) the permissibility (or lack thereof) of these specific customs with regard to their (possible) non-Jewish roots. (I'm particularly interested in references that explicitly consider that the customs' origins are possibly non-Jewish).