Jim Van Buskirk always hated Christmas, but he never knew why.

Getting dragged to a Methodist church with his father at a young age stirred similar revulsion, as did hearing the comments from those who repeatedly told him years later to “get over it” and accept his Christian roots.

Van Buskirk could not be persuaded, however, especially since he was fascinated with Jewish life and culture — but again, he never knew why.

At age 55, his questions have finally been answered.

About two years ago, the San Francisco resident reunited with his mother, Anne-Marie Van Buskirk, after many years of no contact. The time passed quickly that day, a simple lunch turning into a four-hour discussion about his mother’s past. Then the conversation shifted to her son.

“She looked right at me and said, ‘There’s something I have to tell you,'” Van Buskirk said. “She said, ‘I don’t want you to read about it after I’m dead.’ I had no idea what she was about to say.”

She uttered three words that would change her son’s life: “You are Jewish.”

“I was just sort of stunned,” Van Buskirk said. “Before she said another word, I knew it was true.”

But how could he have known? It certainly wasn’t his last name (“Van Buskirk” came from Dutch settlers in America) that gave him any indication of a Jewish identity. It also didn’t help that his mother had completely renounced all ties to Judaism; Van Buskirk even had to stress to her that if he was Jewish, so was she.

Yet Van Buskirk always had known the truth, from the tears he cried when he heard klezmer music for the first time, from celebrating Jewish holidays because it felt “organic,” and from his visits to Jewish museums and Holocaust memorials.

“I used to refer to myself as a ‘Macawannabe,'” said Van Buskirk, using his combined term for Maccabee and wannabe. “I had all the accoutrements of being Jewish, but I wanted to put the pieces together and see what it looked like.”

After Van Buskirk met with his mom, he took the first step toward understanding his Jewish heritage by exploring a suitcase overflowing with photographs of his French Jewish grandmother, Georgette Simon, and letters penned in French and English.

Sifting through what Van Buskirk called a “wildly disorganized treasure trunk” — and finding out that his mother’s parents were, in fact, closeted Jews — prompted him to start writing a memoir, “My Grandmother’s Suitcase.” He hopes to complete the final draft by the end of this year, but will give a sneak preview in the form of an audio-visual presentation Monday, Aug. 4, at Congregation Beth Am in Los Altos Hills.

A year ago, Van Buskirk further immersed himself in Judaism by taking a part-time job at the San Francisco-based Bureau of Jewish Education, becoming the book group coordinator at the Jewish Community Library.

The Los Angeles native also began discovering distant relatives he didn’t even know he had, through research and other means. For example, he recently found out about his second cousin in Seattle. The pair exchanged stories and photographs, and now they stay in touch through e-mail.

“It was amazing to be part of the same family and not know about each other,” said Van Buskirk, whose father died about 20 years ago. “The whole family kept things so secretive.”

Before his mother died in June, Van Buskirk asked her why she kept their Jewish identity hidden for so many years.

She didn’t have an answer, but did mention that a relative told her never to discuss the issue with anyone. It took a therapist’s encouragement for Anne-Marie Van Buskirk to break her silence.

The power of revealing secrets is part of the message Van Buskirk hopes to pass along in his the presentation of his memoir-in-progress at Beth Am. He encourages people to research their families, sit down with photo albums and ask questions — a lot of them.

“It’s really sad because I’m finding out stuff even now,” he said. “I wish I had written down some of the stories, but when you’re 20 you don’t care. At 55, it’s too late.”

But it’s not too late to celebrate his Jewish identity. He recently threw a simcha in his backyard that combined elements of a brit milah, a bar mitzvah and a wedding.

“It was my way of acknowledging my parents and grandparents,” said Van Buskirk, now a member of Congregation Sha’ar Zahav in San Francisco. “I had 50 of my closest friends, people said the blessings, and a woman played klezmer on the accordion. It was fantastic.”

“My Grandmother’s Suitcase,” an audio-visual presentation of Jim Van Buskirk’s memoir-in-progress, is being presented at a meeting of the S.F. Bay Area Genealogical Society at 7:30 p.m. Monday, Aug. 4, at Congregation Beth Am, 26790 Arastradero Road, Los Altos Hills. Information: www.jewishgen.org.