MERLO, Argentina — Luana grabs her sparkly blue dress with one hand and spins, using her other hand as a guide while a strand of tulle floats around her body.

The 8-year-old has long brown curls, gold butterfly earrings and an amulet with a princess hanging from her neck.

“I love it when my hair does this,” she said, shaking her head as her hair flutters. “And I love dresses.”

Luana had to fight to be a girl. She was born a boy, and struggled with a world that insisted that was what she must be. Then, in 2013, she became the youngest person to take advantage of an Argentine law that allows people to identify their own gender for legal purposes.

The case turned the child into an international symbol of progress in the transgender community. At the same time, it sparked a debate in this conservative, Catholic country — the homeland of Pope Francis — about how best to raise children who identify themselves with the opposite sex.

But that discussion — one that has become more and more common around the world — feels very distant from the family’s modest, two-bedroom cement home in Merlo, a small town about 27 miles (43 kilometers) west of Buenos Aires.

“I’ve always been a girl,” said Luana, flashing a smile at her identical twin brother, Elias, the kind of boy who loves remote-controlled cars. He nodded.

“If you gave Luana all my toys, it would not make any difference,” Elias said. “She still wouldn’t be a boy.”

Gabriela Mansilla, Luana’s mother, said there were always clear differences in her twins. Manuel, Luana’s birth name, wore shirts on his head, apparently imitating long hair. He liked dolls. Princesses and mermaids were his favorite movie characters.

Among his first words: “I girl.”

In those first years, slight differences can be seen in pictures of the boys. They are often dressed in identical outfits, but Manuel’s gaze is softer, his head more tilted.

By the time he was 2, Manuel was rejecting pants and insisting on wearing dresses. The struggles were so exhausting that sometimes Mansilla simply consented.

“People in the neighborhood would call me ‘the crazy lady who dresses up her kid,'” said Mansilla, 41.

When the boys were 3, a team of psychologists and doctors prescribed a regimen of “male reinforcement” for Manuel. He would be allowed to play only with male toys like action figures and wear boys’ clothes. The color pink was prohibited, as were cartoons with female protagonists.

While there is widespread agreement in medical circles that some children are simply born with such tendencies, there is little consensus on the best way to deal with the behavior.

Michael Bailey, a psychology professor at Northwestern University who has researched the topic extensively, argues that it’s better for children to accept their birth sex — if for no other reason than to avoid having to contemplate a painful and traumatic sex change. Bailey says long-term studies of boys with female tendencies show that when parents reinforce that they are boys, most turn out to be gay men who accept their gender.

“I feel for parents in this situation and I’m glad that societies are changing to become more tolerant of transgender people,” said Bailey. “But the advocacy here has lost sight of what we know about kids like this.”

But other child specialists, along with transgender advocates, argue that nobody but the individual can decide.

“Somehow we are supposed to prove our gender, but nobody else has to prove their gender,” said Mara Kiesling, executive director of the National Center of Transgender Equality, based in Washington. “It’s not a choice. Kids just know who they are.”

Sabrina Gabrielle Melo Bolke, an Argentine transgender woman who has befriended the family, said she has warned Luana that she will have to make tough choices about hormone therapy when she is a teenager, and ultimately whether to have a sex change.

Still, Bolke, who said she always knew she was female but couldn’t act on it until she was an adult, believes the early gender change will help Luana growing up.

“I wish I would have had the same chance,” she said.

Luana said she remembers her mom trying to make her a boy. Mansilla said the male reinforcement destroyed their family life.

Manuel frequently banged his head against the wall. Patches of hair fell out. He would pull at his penis, explaining in toddler logic that he used it in daycare but at home no longer wanted it.

Nights were so difficult that Mansilla took Manuel to a sleep specialist. A study found the child awoke dozens of times an hour for unexplained reasons.

The battle raged away from home, as well. There was the woman in the toy store who told Luana the doll she had picked out was “for girls.” And in daycare, when the children had to line up, the teachers forced her to go with the boys.

“Everybody told me, ‘No. Get in the line for boys,'” said Luana, whose two front teeth are coming in. “I didn’t listen.”

She began calling herself Luana. About the time she was 5, Mansilla reached out to the Homosexual Community of Argentina, a gay rights group.

“Just let her be a girl,” Mansilla remembered being told, and she agreed.

Argentina’s congress, meanwhile, was debating one of the most far-reaching transgender laws in the world. It would allow for a legal change of gender with only a person’s say-so. The few other nations that allow such a change often have many requirements, from an actual sex change to court orders.

Despite strong opposition from the Roman Catholic Church and Cardinal Jorge Mario Bergoglio, the archbishop of Buenos Aires who would be named pope three years later, the law was passed in 2012.

Mansilla petitioned for Luana’s legal gender change in December 2012. Registry officials refused because of the child’s age, and the case played out in the media. Ten months later, Daniel Scioli, the governor of the Buenos Aires province and now a presidential candidate, intervened. Luana’s petition was granted.

“I remember signing my DNI to be a girl,” she said, referring to her national identity card. She grinned.

Second-grade teacher Judit Lacoa said that when Luana enrolled in her state elementary school last year, many parents were wary. But they’ve adjusted, she said.

The eight girls and 13 boys in the class have taken it in stride. That Luana uses the girls’ bathroom is not an issue. Once, Locoa said, when one of the girls asked Luana why she had a penis, a friend jumped in.

“She’s transsexual,” the child explained nonchalantly, remembered Lacoa.

That level of comfort is no doubt in part because Luana herself appears so at ease. Ask her to define transgender and she will say, matter-of-factly, that “trans girls have penises” and “trans boys have vaginas.” And when, in a recent recess game of “truth or dare,” a classmate asked her whether it was true she was a boy, she did not hesitate.

“No,” she said. “I’m a girl.”