When Erin Jennings walks out of her Bel Air home, she wears a dress.

With a barrette on her short cropped hair, Jennings, who is still biologically male, has recently begun what is known as a “transition”: the process of changing her appearance to align it with the gender she feels defines her.

“I grew up in Texas and my step-father always wanted me to play sports and I wasn’t interested,” she said. “I always knew this was me.”

Jennings, 26, along with dozens of fellow members of the Maryland transgender community, gathered at a McDonald’s in Rosedale Monday evening to show support for Chrissy Polis, a transgender woman who was repeatedly beaten inside the restaurant last week by two people who encountered her in the bathroom and accused her of being a man.

The attack captured on a video has since garnered worldwide condemnation for its brutality as the duo was shown administering vicious head kicks followed by one woman dragging Polis across the floor by her hair as onlookers laughed.

“This is something that is too common,” said Jenna Fischetti, spokeswoman for the Transmaryland, a group that advocates for transgender people. “Although it does not always get this much attention.”

The beating has led to charges of first-degree assault against Teonna Monae Brown, 18, and second-degree assault against an unidentified 14-year-old

But the severity of last week’s attack was seen as teachable moment for advocates who said it highlights the hostility transgender people face, much of it caused by misapprehension of why people seek to change their sex in the first place.

“We are human beings,” said Jennings. “The other day I walked out of my house and one my neighbor said, ‘What the f---? A dress?’”

Added Fischetti: “Many transgender are simply targets.”

They’re targets because transgender men or women are part of a movement that thinks the idea of gender is less about biology and more about how a person thinks — an idea that has been widely debated and garnered support from some politicians, academics and scientists, but which advocates admit is not wholly understood by the public at large

“Gender is a construction,” said Reece Bruce, who is taking male hormones to alter his appearance and attended the rally with his wife, a woman. “Science shows that some species change their sex to correct a gender imbalance, so it is not unnatural. The whole gender idea is too binary.”

Indeed, the debate over what defines gender among the transgender community is wholly different from the “Men are from Mars, women are from Venus” riff that casts gender in stark, well-defined roles.

For members of the LGBT community (Lesbian, Gay, Bi-sexual, Transgender) the accepted traits of masculinity and femininity are thought to be conditioned responses that do not necessarily indicate what’s going on inside a person’s mind.

At its core, gender is about the brain, not just the body, they say.

“Over the past 16 years evidence has been produced that shows that the brains of transwomen are female, not male, which would be a demonstrable if it could be scanned. That day will come soon,” said Dana Beyer, a Bethesda-based physician and a transgender herself who sits on the board of the National Center for Transgender Equality.

To illustrate this idea to her sex education class she teaches at Montgomery County Community College, Beyer offers the example of male soldier who is wounded by a land mine and loses part of his genitals.

“I ask them, what do you consider yourself, a man or a woman?” she said. “The men usually say they would still consider themselves men, which proves my point: It’s not what’s between your legs.”

The notion that we act out gender roles beyond physical appearance and hormones first gained traction with the 1991 release of a book by feminist Judith Butler called “Gender Trouble.”

In it, Butler argued that traditional notions of what it means to be masculine or feminine were not natural, but merely set of artificial norms imposed by a society seeking to limit the possibilities of sexual identity.

Put simply, for Butler gender is more akin to a spectrum than something definitive, said M. Paz Galupo, a professor and director of LGBT studies at Towson University.

“Gender is enacted or performed through repetitive actions (such as standing or sitting in particular ways) that signal masculinity and femininity — this is the idea that all individuals are taught to “perform” gender — and this performance, again, is used to code or classify individuals into categories of male and female."

The rethinking of what gender means has been accompanied by changes in the perception of transgenders in the medical community. Gender Dysphoria or Gender Identity disorder is now an accepted psychiatric condition, a classification which offers medical help to people who want to change their gender.

“When I was growing up as child in sixties they didn’t know what do to with me,” said Donna Simone, a transgender woman and musician from Baltimore who attended the rally. “It was very difficult even though I knew I was women as far back I as can remember.”

This was the case for Polis, says her mother, Renee Polis who said she supported her daughter throughout the process of changing her sex. “When she was young I used to buy her trucks and she wanted Barbies ... “She always knew.”

Still, the violent encounter at McDonald’s has shed light on the gap in public acceptance that can have violent consequences, advocates warned.

“Education is slow,” said Beyer. “It took us three years to add gender identity to the sex ed curriculum in Montgomery County, of all places, and we had to spend years in court defending it.”

Along with the gap in educational outreach is a lack of real data on how often these types of attacks occur.

“My understanding is that data regarding anti-transgender hate crimes are not currently being collected in Maryland,” said Galupo. “Nationally, the information regarding violence directed to individuals in our transgender communities is incomplete, is often based on self-report surveys, and does suggest that anti-LGBT hate crimes are actually increasing.”

Still, for transgender women like Jennings, the biggest hurdle is getting people to understand that the process of realizing their sexual identity is an expression of their own sense of self, not an affectation.

“The representation of transgenderism in the media often misses the most important element, that we’re human,” she said. “It’s about who I am. Now I can let myself be myself.”