Can a 5-year-old’s parents know he’s transgender? Yes.

The story of Jacob Lemay, a 5-year-old transgender boy, has gotten a lot of attention in the past week due to some great coverage by NBC News’s Kate Snow. But for some, Jacob’s story has raised questions about how parents can know for sure whether their child is really ready to transition at an age as young as 5.

But knowing their gender identity at an early age isn’t out of the ordinary for transgender people, who identify with a gender different from the one assigned to them at birth.

This early realization is something I heard from various people in trans communities while conducting a series of interviews to better understand their everyday lives. “I always knew,” said Jordan Geddes, a 26-year-old trans man in Columbia, Maryland. “But I grew up and had the whole world telling me I’m wrong. At that point [as a child in the 1990s], there was no visibility whatsoever about trans issues. My parents just assumed I’m a very butch lesbian.”

It’s also something backed by current research on gender identity. A recent study from the TransYouth Project found that trans children as young as 5 respond to psychological gender-association tests, which evaluate how people view themselves within gender roles, as quickly and consistently as those who don’t identify as trans. And a review of the research by Boston University School of Medicine experts concluded that the available data suggests there’s a biological link to a person’s gender identity, indicating that trans people are essentially assigned genders at birth that don’t match their inherent, biologically set identity.

So how do parents know for sure? Jacob’s mother, Mimi Lemay, explained that there are some signs: “[Jacob’s] need to play boy roles and [Jacob’s] need to be seen or spoken to as a boy at home became very persistent and very consistent. Those are the hallmarks of a possibly transgender child: consistence, persistence, and insistence.”

In the case of Jacob, who’s in preschool, his parents recalled repeated claims that he is, indeed, a boy. Some of his happy early moments, shown in NBC News’s coverage, were in a trip to Disneyland where he dressed as Prince Charming. When his parents approached him about transitioning and changing schools so everyone at his new school would know him as a boy from the start, Jacob said yes. “He said, ‘I want to be a boy always. I want to be a boy named Jacob,’” Mimi Lemay said.

Giving Jacob the opportunity, his parents said, completely transformed his mood. “Before the transition, he didn’t smile a lot. I had never seen him throw his head back and laugh — like really laugh,” his mother said. “He started looking people in the eye. He started talking about people — ‘That’s my friend.’ And I realized how much he had come out of his shell, and how much being Jacob suited him. And I realized he had never really been Mia — that had been a figment of my imagination.”