Sabrina Mangat, 21, is a pre-med student at Howard University who wears bright T-shirts and jeans. Her brother, Vikram, 18, is a lanky basketballer with punkish short hair and a diamond ear stud. Both describe themselves as devoted to the Sikh faith that their parents brought from India — a commitment they say intensified after a gunman’s rampage Aug. 5 at a Sikh temple in Wisconsin, which left six people dead.

But like tens of thousands of Indian American Sikhs growing up in the United States, the siblings have grappled with how fully to embrace the distinctive garb and demanding customs of a faith that is often misunderstood here. Even at a young age, many Sikhs are taunted by classroom bullies or insulted by strangers as Taliban or al-Qaeda followers.

“Being a Sikh has always been an important part of my life, but so far it has been more spiritual than outward,” said Sabrina, who helped lead a youth vigil last week outside the White House. “I admire those friends who keep their hair, get baptized and pray five times a day, but I’m not there yet.”

Vikram, an easygoing jock, has been forced to make a stark choice about whether to leave his hair uncut, an important sign of Sikh piety for both sexes. Sikh girls can blend easily, facing little more than curiosity about their long tresses. But for a teenage boy, wearing a head net or turban to soccer practice can take enormous courage at an age of intense pressure to conform.

“When I was little, I had [long] hair, then I cut it, then I had it. Then in the 10th grade, I cut it again,” said Vikram, whose sister recalled someone yelling “Osama” at him after the attacks of Sept. 11, 2001. “It was all part of a process. Growing up is a process. If I cut off my hair, I can still be a good person, but I’m not a good Sikh. It can be a fine line in life.”

For many young Sikhs in the Washington area, mostly children of immigrants from India, the attack in Wisconsin reinforced pride in their religious identity at a time of national sympathy. Rather than retreating into suburban enclaves, some have seized the opportunity to showcase Sikhism — a monotheistic faith founded in South Asia several hundred years ago — as a religion of inclusivity and love.

But even strengthened convictions don’t necessarily translate into adopting the full Sikh look. While young Sikh children here generally follow parental dictates, those in high school and college may experiment with American culture and fashion. In some families, this can cause great tension, but other parents say they let their kids find Sikhism at their own pace.

“We are a diverse family, and diversity is strength,” said Harpal Mangat, 52, the father of Sabrina and Vikram. A Potomac doctor who emigrated from London, he is a keen student of Sikh history and beliefs but said he wears a turban only on special occasions. His wife, also a doctor, is more devout.

“Some families start building their children’s identity on the outside and then build on that, but it can go the other way, too,” he said.

The young Sikhs who organized the White House vigil Wednesday, mostly college-age friends from Montgomery County, wore an assortment of clothes and hairstyles as they gathered supplies and marshaled volunteers. For the event itself, they donned hand-painted shirts that read “United Against Hate.” Among them was Sehej Kaur, 20, who looks like a ponytailed gymnast but can recite hours of Sikh hymns in an Indian dialect.

“I have never felt prouder to be a Sikh,” said Kaur, who stopped painting shirts to untie her ponytail and let down her waist-length hair, which she said symbolizes the Sikh belief in keeping “whatever God gave you.”

Gurshean Singh, 30, a teacher from Philadelphia who volunteered to help at the vigil, wore a red turban. Singh, who has a flowing black beard, described his religious upbringing as “very strict” and said his faith deepened as he learned about Sikh suffering in history, then saw fellow Sikhs harassed after Sept. 11.

“Sikhi is a way of life,” Singh said, using a term for Sikh culture. He said he would only marry another Sikh and wanted to “bring up my kids in a Sikh environment,” yet he said he has close friends who cut their hair and abandoned wearing a turban.

“We have to respect free will,” he said. “We discuss it, but we don’t judge.”

Although Sikh leaders in Washington sought to project a message of forgiveness and optimism last week, the shooting in Wisconsin brought out flashes of anger and pain.

Natasha Kaur, no relation to Sehej, spoke at the vigil. Kaur, 30, a resident physician at George Washington University Hospital, described with visible anguish how 22 years ago, her little brother was knocked off his bicycle and had his pants pulled down by neighborhood bullies. Then her tone became defiant as she addressed the dead Wisconsin gunman.

“You don’t know who we are,” she said, “but we wear our faith on our heads to show our values. You don’t scare us.”

When strangers come up to Dilroop Sidhu, a law school student in Washington who helped organize the vigil, and ask her why her hair is so long, she said, “I just give them the elevator speech” — a one-minute synopsis of basic Sikh tenets.

“Every Sikh child in America learns to explain themselves quickly,” she said.

Among young men at Wednesday’s vigil, some wore turbans in brilliant saffron, a traditional Sikh symbol of strength; others had close-cropped hair. One teenager on vacation from a religious school in India wore a full ceremonial uniform, including a long skirt with a silver dagger at the waist.

But some Sikhs with short hair were no less devout. Amit Bagga, 26, a former congressional aide, said he had been raised in a Hindu-Sikh home and felt “divorced from my Sikh identity for a long time.” After Sept. 11, he started reading and thinking more about his Sikh heritage. But it took the Wisconsin massacre, he said, to crystallize his identity.

“It was very catalytic for me,” Bagga said. “I’m not a religious person, but I suddenly wanted to be seen as a Sikh . . . and not be afraid of it.” He was not prepared, however, to wear a turban to the rally. “Unfortunately, this is a realization I came to only yesterday,” he said.

A number of Sikh families brought children, including young boys wearing red or green cloth topknots. Ravi Singh, 48, a technology consultant from Rockville, was there with his son Sehej, 14, who said that fewer schoolmates tease him now than when he was younger but that some “still have no clue. When they think turban, they think ‘terrorist.’ ”

Singh said that he had never considered cutting the boy’s hair but that he and his wife made repeated visits to Sehej’s schools to explain their faith and culture. They were also part of an ongoing campaign to press Montgomery schools to include Sikhism in religion classes. He said Sehej, once the only Sikh boy in his school, gradually became so accepted that he was named vice president of the student government.

“The bigger issue we have to address is not about us. It is about hatred, whether against Jews or Muslims or any group,” Singh said. “It affects all of us. We have to find a way to get the next generation to be more tolerant and loving.”