The irony that looms large in 23-year-old Harvard Law student Rebecca Katz's life these days is this: It was only when the Fifth Commandment's exhortation to "Honor thy father and mother" became meaningful to her that she ran afoul of her parents.
While Katz has always known she is Jewish, Judaism never played a role in her life. Her family was so assimilated that every year they decorated a Christmas tree.
Now, though, Katz is on a journey to reclaim her Jewish identity. Most Friday nights she celebrates Shabbat with other Harvard students, reciting Hebrew prayers and pouring water over her hands in a ritual before blessing the bread.
She's learning Hebrew and thinking a lot more about God. Her parents are not pleased.
"My mother explicitly used the word 'rebellion.' She feels very much that I'm doing this to get back at her," Katz said. "Before, I didn't really care about honoring my mother and father. It's strange, because now I feel very strongly about honoring them, but there's this enormous strife."
Young adults reared in households where religion was almost invisible are turning in significant numbers to traditional forms of Judaism. They are called ba'alai tshuvah, or "the returning."
To many of their parents, however, these young people aren't "returning" to anything. Rather, they are embracing something that was never a part of their lives. Parents are bewildered by daughters who won't wear pants or sons who wrap tefillin around themselves to pray, alien offspring who seem to be rejecting their upbringing.
"Our first reaction was, 'Oh my gosh, where is this coming from?"' said Harriet Gilman, a children's librarian who lives in the Chicago area. Her daughter, Boston resident Joy Greenwald, 24, started attending weekly services and keeping kosher when she was an undergraduate at the University of California at Berkeley.
"It was a total departure from the way our family had lived," Gilman continued. "We really didn't understand why she would choose to do this."
Even parents who strongly identify with Judaism and belong to Reform or Conservative branches of the religion are wary of the trappings of Orthodox Judaism.
Larry Sternberg, associate director of the Cohen Center for Modern Jewish Studies at Brandeis University, several years ago conducted a workshop exercise that revealed the intensity of emotion swirling around the question of how to be a good Jew.
Sternberg asked Jews to rate, in the abstract, a potential son-in-law or daughter-in-law. Among the choices were a non-Jew and a Hasidic Jew.
Most parents said they would be less concerned if their child married the non-Jew. Sternberg believes the results might be more mixed today, given worries about how intermarriage could threaten the future of American Judaism.
Still, he said, many parents feel that a child who becomes very religious is critiquing his or her elders' way of life more than a child who shows little interest in Judaism.
Ask most Jews today, and they'll tell you about a son or a cousin or a friend who has become observant in young adulthood. Thirty to 50 students regularly attend Friday night dinners at Chabad House of Boston, and the same number at Chabad House at Harvard Square, both led by Lubovitch rabbis who make a life of tutoring Jews to become more observant.
The history of Jewish life in America helps explain why so many young adults are examining their faith, suggested Jill Ringel, a 21-year-old Northeastern University student, who is ba'al tsheuvah.
"It's a natural occurrence in American society after generations of assimilation," Ringel said. "We had to go through that pulling away so we can come back."
Several academicians buttress Ringel's point, noting that today's young American Jews, usually fourth- or fifth-generation Americans, have lost the craving to blend in that many of their parents and grandparents felt.
Those Jews who never "assimilated" have often constructed their identity in secular ways by, for example, championing Israel, said Jonathan Sarna, a professor of American Jewish history at Brandeis. Now an established state, Israel is less likely to "animate" American Jews, Sarna said.
"There's a turning away from an emphasis on ethnicity to an emphasis on religion and faith as the glue that will hold Jews together," he said.
While most young Jews today are less connected to Judaism than ever, Sylvia Barack Fishman, professor of contemporary Jewish life at Brandeis, said a core group - 25 to 30 percent - is actively seeking to connect with its heritage.
"It's not just the numbers that are important, Fishman said. "It's out of that smaller group that leaders are going to come."
Ringel, the Northeastern student, might become one of those leaders - certainly, she is as enthusiastic about religion as a 21-year-old could be. And that has strained her relationships with family and friends.
Ringel went to Hebrew School and grew up celebrating Jewish holidays. But her family didn't keep kosher or light candles on the sabbath. Nor did they consider themselves religious.
Once in college, Ringel started reading about the symbolic meaning behind Torah laws. "It all seemed so beautiful to me," she said.
Slowly, over a couple of years, she added more and more Jewish customs to her daily life. She began by eating kosher food and saying a blessing before her meals. ("Eating is not just eating, it's connecting to God," she says.)
Orthodox Jews take literally the notion of Shabbat as a day of rest. Turning on a lamp or making a phone call qualifies as "work." So Ringel first stopped watching television on Shabbat, then stopped driving, and later started unscrewing the light bulb in her refrigerator on Fridays.
Now Ringel, a senior studying physical therapy, wears long skirts and sleeves that cover her elbows, for modesty's sake. She observes a custom for single women, called shomer negiyah,which dictates that she cannot touch men. She exudes zest for the laws that her parents fret are restricting her.
"All of a sudden I wanted so much to wear skirts all the time," she said. "It's very exciting. It's the first time you're showing your Judaism to everybody."
Ringel easily found a community to support her, in places such as the campus Hillel and Chabad House of Boston. In fact, the strong sense of community is one big draw of Orthodox Judaism. But Ringel also says she felt at odds with the people who had been in her life. Friends took offense, for example, that she wouldn't go out to clubs with them anymore.
Ringel's parents, who live in New Jersey, were angry that she didn't want to eat at home or go to favorite restaurants, that she refused to drive to see her grandparents on a Saturday.
"I don't agree. It's not my lifestyle," said Jeffrey Ringel, who works in sports television. "There's a separation in our relationship, I feel."
After two years, it's still difficult. While her parents deny it, Ringel, like many ba'alai tshuvah, believes they see her lifestyle as an implicit criticism of the way they raised her.
Minor disputes often become flash points for serious conflict. Harriet Gilman loves to cook, and it still pains her that her daughter will not eat, say, her sausage lasagna.
"I don't think it makes any logical sense," said Gilman's husband, Alan, an oncologist, of kosher laws. "It doesn't have anything to do with the modern world."
Yet the Gilmans remain close, as do the Ringels. Jill Ringel canceled plans to go to Israel this summer so she could live at home and let her parents and brother become accustomed to her new ways.
And her parents say they are coming to terms with the life their daughter has chosen. "She's still her," said her mother, Barbara, a teacher. "She's still silly, she's still serious. She still laughs, she still cries."
In the words of Rabbi Shmuel Posner of Chabad House of Boston: "After a while, the parents realize it's not crazy, it's not nuts, it's Jewish!"
Sometimes, said several rabbis, parents are inspired by their children and become more observant themselves. In other cases the child comes to realize that he or she may have been a little self-righteous in the first blush of newfound passion.
"In the beginning, I almost wanted to change my parents," said Alanna Goldberg, 24, who transformed from a self-described party girl to a ba'al tshuvah while at Boston University. "It took me a while to learn to respect their lifestyle."
A common refrain of young, newly observant Jews is that little is more important to them than paying respect to their parents and to their ancestry. Amit Kiesel, 26, crams Torah study into his hectic schedule at Harvard Business School.
"I can tell you so much more about the wireless industry or the Internet than my father's religion and my father's father's religion," said Kiesel. "It makes me sad that I don't know anything about Judaism because it's so much more important than what I do know about."