Thanksgiving usually consists of cooking on a level that Jews do every week for Shabbat preparation — soup, salad and all those sides that accompany the main dish.
And while chicken has been a staple from the agricultural era and was never a stranger to kashrut, the turkey was initially an unknown bird, as it didn’t exist in the Old World, thus presenting a dilemma about whether or not it was acceptable for Jews to eat according to dietary laws.
Rashi said that only birds that had been traditionally eaten by Jews could be considered permissible to eat; hence, any new birds discovered could not be deemed kosher.
Although the turkey appeared in Jewish legal literature in the 18th century, the issue surrounding whether or not the New World bird was kosher had been decided primarily because the Mishnah Hullin dealt with new, unfamiliar birds. For kosher certification, birds must consist of specific physiological features: a crop, an extra toe and a muscular, thick-walled part of its stomach that is easy to peel.
Additionally, there is a behavioral requirement in that kosher birds cannot have particular kinds of predatory manners.
Jews celebrating Thanksgiving in Israel are, like most of their counterparts in the United States, not frowned upon in that, along with observing Jewish law, Israelis annually consume twice as much turkey meat as Americans do.
And as a last (and very important) note, the Hebrew word for “Jews,” yehudim, comes from the root of the Hebrew word hodu, or “to give thanks”; it’s also Hebrew for “turkey.”