For families, it can be a long, emotional adjustment. Shortly after her son’s third birthday, Pam B. and her husband, Joel, began a parental journey for which there was no map. It started when their son, J., began wearing oversized T-shirts and wrapping a towel around his head to emulate long, flowing hair. Then came his mother’s silky undershirts. Half a year into preschool, J. started becoming agitated when asked to wear boys’ clothing.

En route to a mall with her son, Ms. B. had an epiphany: “It just clicked in me. I said, ‘You really want to wear a dress, don’t you?’ ”

Thus began what the B.’s, who asked their full names not be used to protect their son’s privacy, call “the reluctant path,” a behind-closed-doors struggle to come to terms with a gender-variant child — a spirited 5-year-old boy who, at least for now, strongly identifies as a girl, requests to be called “she” and asks to wear pigtails and pink jumpers to school.

Ms. B., 41, a lawyer, accepted the way her son defined himself after she and her husband consulted with a psychologist and observed his newfound comfort with his choice. But she feels the precarious nature of the day-to-day reality. “It’s hard to convey the relentlessness of it, she said, “every social encounter, every time you go out to eat, every day feeling like a balance between your kid’s self-esteem and protecting him from the hostile outside world.”

The prospect of cross-dressing kindergartners has sparked a deep philosophical divide among professionals over how best to counsel families. Is it healthier for families to follow the child’s lead, or to spare children potential humiliation and isolation by steering them toward accepting their biological gender until they are older?

Both sides in the debate underscore their concern for the profound vulnerability of such youngsters, symbolized by occurrences like the murder in 2002 of Gwen Araujo, a transgender teenager born as Eddie, southeast of Oakland.

“Parents now are looking for advice on how to make life reasonable for their kids — whether to allow cross-dressing in public, and how to protect them from the savagery of other children,” said Dr. Herbert Schreier, a psychiatrist with Children’s Hospital and Research Center in Oakland.