When Do Kids Know They’re Transgender? Younger Than You'd Think

When Kristina Olson, a psychology professor at the University of Washington, started looking into research on transgender children, she was surprised. It was thin at best.

Data from decades ago said that 80 percent of transgender kids revert to their born gender, but Olson was skeptical.

So she started the TransYouth Project to track transgender children to adulthood. The project has worked with 65 children across the U.S. and Canada – so far. Some are as young as 3.

Olson calls these kids "gender pioneers."

“What is the impact of being allowed to live your gender identity?” Olson said. “Nearly all transgender adults today were not allowed to live as their gender identity as kids, so we just don't know what life is going to look like for them.”

Olson spoke with KUOW’s Marcie Sillman about transgender kids – and what age their parents consider giving them hormones or hormone blockers. Highlights from the interview below.

How can you tell if a child is really transgender?

We don't have some magic test.

A lot of these kids have been persistent and consistently identified as their gender identity. This isn't a passing phase. This doesn't seem to be something that just crops up one day and goes away.

And importantly, they are saying, “I am this thing.”

Sometimes we hear from parents that the parent says, “Well, you could just be a boy who likes to wear dresses,” and the kid says, “No, it's not the dress. I am a girl.”

That seems to be the crucial difference between a boy who likes a girly things and a boy who is saying, "I am a girl."

Do you know where in a human being a body or mind gender identity comes from?

No, I wish we did.

Some people have theories about gender identity and behavior being linked to in utero hormones.

There's some work that's being done on genes. There's been some work on environment; there are just all these different factors that seem to come to play.

WATCH: Mama, I Was Supposed To Be Born A Girl

How early might a child express gender identity out loud?

We have heard reports as early as when their kids start talking, as soon as they could say words like girl and boy. So a lot of parents say 18 months, 2 years.

Parents didn't think much of it, so they thought, “Oh, my kid doesn't know what the words ‘girl’ and ‘boy’ mean, or I couldn't figure out why my kid wanted to wear high heels or dresses.”

When does a family decide to use hormones?

The earliest stage that I'm aware of in the United States is usually once the process of puberty has started a little bit.

I should say that at that point the decision is whether to put a kid on something called hormone blockers. Blockers stop physical puberty from progressing.

That's really different from what we call cross-sex hormones, which are cause something that looks a little more like puberty in somebody of a different sex.

Hormone blockers are completely reversible. If you take a child off of them – if a different decision is made – the child goes through their natal puberty. Some parents use them as a first step before cross-sex hormones. Some people use them to take a little bit more time to make a decision about what the child's going to do.

How many people are transgender?

Estimates are ALL over the map. I don't think anyone actually knows. I've seen numbers ranging from 1 in 300 to 1 in 100,000. Seriously.

Questions and answers have been edited and condensed.

This segment originally aired Jan. 29, 2015.