Tyler, 7, sports a self-styled mohawk as he plays at his home in a Maryland suburb near Washington. (Nikki Kahn/The Washington Post)

He knew it at 2 years old. His parents suspected it at 4 and knew it at 5.

And now, as he turns 7, the courts know it, too.

The child born into a girl’s body with the middle name Kathryn, who insisted from toddlerhood that “I am a boy,” had a legal name change this year. Tyler is now his official middle name. (The Post is not using his first and last names to protect his privacy.)

It’s another milestone in the long and gut-wrenching path for an otherwise average Maryland family that decided to ignore conventional wisdom and let their child be who he says he is.

Two years ago, I wrote a profile of their struggle called “Transgender at Five” that shocked some readers and inspired others. Since then, Tyler’s parents, Jean and Stephen, have seen a massive change in the world around them.

Tyler swings in a hammock at his home. (Nikki Kahn/The Washington Post)

Earlier this year, D.C. Mayor Vincent C. Gray (D) directed health insurance companies to cover treatment — including gender-reassignment surgery — for city residents with a diagnosis of gender dysphoria.

Last week, Maryland Gov. Martin O’Malley (D) signed a measure prohibiting discrimination against transgender people in ­cases of housing, employment, credit and the use of public bathrooms.

Also last week, Defense Secretary Chuck Hagel said he was open to reviewing the Pentagon’s prohibition on transgender people in the military. And this month, Oxford University Press launched “Trans Bodies, Trans Selves,” an exhaustive, nearly 700-page health book for the transgender community.

“It’s already a different world, and it’s becoming a better world for my child,” said Tyler’s mother.

The one thing that hasn’t changed much? Tyler.

“Yes, he’s still a boy. It’s not a phase,” she said, weary, but patient with the constant inquiries — “So, how is it going?”

The family agreed to interviews because they know that their child is not alone and want to advocate on behalf of other children whose belief that they were born into the wrong gender — the clinical term for that is gender dysphoria — may be difficult to live with in a society that insists on rigid gender roles.

Most of their friends and neighbors and their children’s classmates know that Tyler was born as Kathryn, and the family doesn’t hesitate to discuss it with anyone who asks.

Tyler used to issue a blanket statement to friends about being transgender. But lately, he doesn’t want to talk much about it. Almost as if he’s forgotten that he’s different.

He may change his mind about being a boy when puberty hits, according to doctors who specialize in children with gender-identity issues. Or he may ask to get hormone injections to begin growing the biological characteristics of the opposite sex when he is 15 or 16 and fully transition with gender-reassignment surgery once he is an adult.

When Jean and her husband first began to educate themselves about transgender children, the support groups they found were mostly made up of adults or teenagers. They felt alone until they found one other family with a young transgender child. Then another. And another. Now, they have more than a dozen families who meet at their home once a month to talk about schools, bathrooms, siblings and legal battles.

“And we hear from at least one new family every month,” Jean said.

They are comfortable enough with ­changes in Maryland that they will enroll their child in a public school next year. That was unimaginable two years ago, so they went into deep debt paying for a private school that was gentle and understanding. Since then, they’ve seen ­changes in school training, policy and the public conversation.

One of their biggest legal hurdles this year was the name change. Tyler’s birth certificate, insurance card and everything else had the girl name. This became a problem when they visited a doctor, traveled or had any interactions with the official world.

But to change a name legally, the county courts require that a public notice about the name change be published in the local newspaper. That would create the paper trail they’ve been trying to avoid.

So they went to court in February, ready for a fight.

“I was so anxious for everything to go smoothly with the judge that I couldn’t eat,” said Tyler’s dad, Stephen.

But the judge remembered reading about Tyler in The Post. Tyler charmed everyone in court and the change was made under a sealed document.

Transgender at 7? Not too different from raising any other 7-year-old boy.

Twitter: @petulad

To read previous columns, go to washingtonpost.com/dvorak.