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When California Congressman Mike Honda tweeted a photo of himself on Twitter back in February, grinning next to his beautiful 8-year-old granddaughter Malisa, it went viral right away — and not just because it was cute.

"As a proud grandpa of a transgender grandchild,” the eight-term Democrat wrote. “I hope she can feel safe at school without fear of being bullied."

With those words, Honda had chosen to make a private family matter very public.

“I think that there's a time when you have to determine when there's...a good teaching moment. And I think that was one of them,” Honda, a former teacher, told NBC News.

WATCH: NBC's Kate Snow report on Malisa's story

His daughter, Michelle Honda-Phillips, saw it as typical grandparent pride.

"I think a lot of grandparents who are social-media savvy, or who are on Facebook or whatnot, talk about their grandchildren all the time. They post pictures about their grandchildren, their families. He did nothing different,” she said.

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As far back as the ultrasound, Honda-Phillips and her husband, Travis Phillips, thought their second child would be a boy. But by the time their child was three, she had chosen a new name for herself — Malisa.

Malisa, before her transition. Courtesy Phillips family

“She wanted the princess gowns and the princess heels and the tiaras and the wands. She had 'em all,” Michelle said.

And it wasn’t just dress-up. Malisa says she felt different on the inside.

“Like I was a girl, not a boy,” she explained.

On her eighth birthday last summer, Malisa’s parents asked everyone to start calling her that and using the pronouns “she” and “her.” It was the start of a new life, known in the transgender community as a “transition."

Although there are no exact numbers, Malisa joined what experts say is a growing number of children transitioning at a young age. The changes are cosmetic: a new name, new pronouns, new clothing. There is no surgery or hormonal therapy involved at this age.

WATCH: One doctor explains how younger children transition

Malisa’s family sees themselves as lucky because their friends and family have all been very supportive. And after grandpa the congressman sent that tweet, the reaction was overwhelmingly positive, they say.

“We showed Malisa the positive responses that it was getting. And I said, ‘You're like a rock star. Everyone knows who you are.’ She says, ‘Well, I think I'm more like a pop star.’

“I have people finding me on social media saying, you know, ‘You've helped us be able to tell our parents.’” Michelle said with tears in her eyes.

“They see someone like my father, who is a grandpa, but who is also, you know, very well-known. And they feel like, ‘Well, then maybe this is something we should be supportive of or learn more about.’”

As the proud grandpa of a transgender grandchild, I hope she can feel safe at school without fear of being bullied. pic.twitter.com/NDIfOdW9sk — Rep. Mike Honda (@RepMikeHonda) February 18, 2015

The family knows they are just at the beginning of this journey with Malisa and work closely with a team of doctors. As she approaches puberty, they’ll have to consider whether to use so called puberty blockers and hormone therapy.

“So we are going in a month to just get her bloodwork done, just to see where she's at," Michelle said. "I would imagine we have a couple of years before we have to think about anything. But we wanna make sure that we are supporting her every step of the way and being just knowledgeable about what's coming.”