Growing up in San Francisco, almost every Jewish family I knew celebrated Christmas.

These weren’t half-baked, thrown-together-at-the-last-minute versions of Christmas, either, sops to a dominant holiday. These were full-blown celebrations, with tall trees decorated in tinsel and lights, Santa Claus decorations around the house and sumptuous meals.

And the presents! In houses around the city, among Jewish families whose roots extended back to the Gold Rush, there were heaps and heaps of them, the most fabulous gifts money could buy. Boxes from I. Magnin and J. Magnin, Macy’s and Gumps were stacked in piles around the Christmas trees.

It was not until I was a freshman in college that I realized that this Jewish version of Christmas was an anomaly. Many of my new friends were from the East Coast, and when I described our annual Christmas festivities, they looked at me with strange expressions. “But that’s a Christian holiday!” I heard over and over. “Jews don’t celebrate Christmas,” they insisted. “A proper Jewish Christmas is Chinese food and a movie!”

Their horror over Christmas was just part of a larger discussion of what it meant to be a Jew. My boyfriend at the time had been raised in New York and was Modern Orthodox. He and his father went to shul every Saturday, hats clamped firmly on their heads. My brothers, in contrast, had not even had bar mitzvahs. I only went to temple on occasion.

We were too assimilated, I heard. You West Coast Jews are fakers, others told me.

I still defended my right to celebrate Christmas, but doubt had crept into the discussion. As the years went on, I still did a full-blown Christmas (I had two daughters by then) but it gradually became more of a hassle than fun.

But while researching my book on Isaias Hellman, my great-great grandfather and the former president of Wells Fargo Bank, I learned that my Christmas-loving ways had deep historical roots that had more to do with adapting to life in America than rejecting Judaism.

Hellman came from Bavaria to Los Angeles in 1859, part of a large wave of Jews from Central Europe. He fought hard to retain his spiritual connection in the dusty pueblo that was then Los Angeles. There were fewer than 60 Jews in the city then, and no temple or rabbi, so the community worshiped in rented adobes. Hellman helped raise the funds to construct the city’s first synagogue, B’nai B’rith, in 1873. It is known today as the Wilshire Boulevard Temple, one of the largest Reform temples on the West Coast.

Hellman opened a dry goods store in 1865 and was faced with a moral dilemma: Should he keep his store open or closed on Saturday, the Sabbath? Ultimately, he decided to adapt to American business habits rather than conform to religious tradition.

Hellman’s family also celebrated Christmas. While searching through copies of the Emanu-El, the predecessor to the Jewish Bulletin (which is now j.), I saw a notice that Hellman’s 16-year-old daughter, Florence, hosted a “Santa Claus” party at the family’s house on Franklin and Sacramento in 1897. Furthermore, it appears that these types of celebrations were common. Nestled next to the announcement of the party were ads from San Francisco’s leading department stores suggesting that readers come to their stores to buy Christmas presents.

It turns out that Jews in California have been celebrating Christmas since the 1850s. But they never regarded the holiday as a celebration of Jesus’ birth. It was more of a winter festival and an exchange of presents.

America’s current conception of Christmas did not evolve until the 19th century. While the Catholic Church in the fourth century had designated Dec. 25th the official day to celebrate Christ, for centuries the occasion was more often marked by alcoholic revelry and overindulgence than by spiritual contemplation. The Puritans were so offended by the excess that they banned the holiday. Massachusetts did not make Christmas official until 1856.

The rituals of Christmas — Santa Claus, a tree and Christmas cards — only gained widespread acceptance in the middle of the 19th century. Saint Nick was regarded as a strict Norse god until Clement Clarke Moore transformed him in 1822 into a round, red-cheeked man in ” ‘Twas the Night Before Christmas.” Even then, it took more than 18 years for the poem to become popular.

In fact, the celebration by Jews of Christmas was so widespread — and considered so unremarkable — that Rabbi Jacob Voorsanger, the rabbi of Temple Emanu-El, virtually gave it his blessing in an editorial for the Emanu-El in 1904. “Christmas never supplanted Chanukah in the old Jewish home,” wrote Voorsanger. “Candies and cake and presents and Santa Claus and all the cheerfulness of the social winter feast was borrowed, but not the heathen spirit of forgetting the obligations at home.” That same year the Jewish Council of Women held a debate about the propriety of Jews celebrating Christmas, which was so popular that the group had to turn people away at the door.

When violence against Jews in Russia flared in the 1880s, prompting hundreds of thousands of Jews to flee to America, the Jewish practice of celebrating Christmas came under close scrutiny. The Jews from Eastern Europe clung to their traditions more firmly than the Central European Jews had, and many were critical of what they perceived to be a watering-down of Judaism. This split continues today.

So my research has assured me that my family is not rejecting Judaism when it puts up a Christmas tree and drapes it with lights. We are not celebrating Jesus, either. We are celebrating a winter holiday and continuing a tradition rooted in the early days of California. I do not expect that most Jews will join us, but I hope for some open-mindedness when I explain why there are Christmas lights sparkling next to our Chanukah menorah.

Frances Dinkelspiel is the author of “Towers of Gold: How One Jewish Immigrant Named Isaias Hellman Created California.”