The YouTube video captures a gregarious teenager, talking to you from her bedroom. Crossed field hockey sticks and a large pink butterfly decorate the wall behind her.

It’s Sierra Zahares, a Freeport High School student, explaining what it’s like to have Moebius syndrome, a rare neurological condition that prevents her from blinking or smiling or showing any facial expression at all.

People with Moebius syndrome often struggle in social situations, Zahares says in the video. While most people might greet each other with smiles, people with Moebius syndrome must find other ways to show interest in the people they meet, such as body language, laughter and “smiling in their own sort of ways.”

“I would know this,” Zahares announces suddenly, “because I have Moebius syndrome!”

The video has been viewed nearly 4,000 times by people as far away as Romania and the Philippines. Comments posted by people with Moebius syndrome praise Zahares for her courage, clear speech and vibrant personality. Some write that they want to be like her.

An only child, Zahares was born with the syndrome and diagnosed as an infant. But her parents never let it hold her back.

“They wanted me to be vocal about it,” Zahares said. “Be yourself. Be confident. Roll with what you’ve got.”

That was difficult in elementary school, when the syndrome was a complicated concept to explain to other kids. Things changed through middle and high school.

A good student, she was elected to be a class officer and served as president of her Girl Scout troop, leading many volunteer projects in the community. In addition to playing field hockey, she has been actively involved in theater and choral groups, singing and dancing in every production for four years.  She has developed a close group of supportive friends, and she has become a champion of Moebius syndrome awareness.

“As I grew older, I realized I had a purpose,” Zahares said.

Zahares has worked with the Moebius Syndrome Foundation to share her story worldwide through videos, live feeds and other projects. She recently published a book of poetry, “Beneath Her Soul,” which she describes as “me sharing my challenges, experiences and advice, so you will know that you are not alone.”

Zahares plans to attend the University of Maine at Farmington and study elementary education and psychology.