A town known for its battle green is now the latest front in the fight over classes about gender and sexual orientation, with Lexington parents debating the “Serious Talks” diversity and inclusion curriculum as the district looks to roll it out more broadly.

The curriculum, which is now the subject of pushback in the form of an online petition, has existed in some form for more than a decade and is currently in use in a handful of schools, according to the district.

Parents and educators mostly voiced support for the curriculum at a recent School Committee meeting, after an online petition called for the diversity and inclusion program to be suspended.

The push to change Lexington’s curriculum is the latest example of what’s become a national trend of conservative groups and right-leaning parents raising objections to certain programs that teach about diversity and inclusion in public school districts.

Last year, Parents Defending Education, a nonprofit based in Washington, D.C., identified 43 “incidents” in Massachusetts schools challenging curriculums that teach about race, gender, and sexual orientation, the Globe reported. As of last week, the organization had identified 63 “incidents,” including Lexington Public Schools, according to its website.

The online petition began to circulate last month about the Lexington curriculum, calling for “Age-Appropriate Education for Our Children” and demanding the curriculum be removed.

But at the School Committee meeting, more than a dozen parents, teachers, and students said the curriculum was critical, while relatively few questioned whether it is age appropriate.

Andrew Harris, a father who identifies as nonbinary, applauded the curriculum and said gender identity is not “too complex” a concept for 6-year-olds to grasp, as the petition claims.

“I know that my 6-year-old would be the first in line to help” trans and nonbinary students feel welcome, Harris said.

Superintendent Julie Hackett said the district is “unapologetically committed” to inclusion and she was “heartened by the showing of support” at the meeting. She said the district planned to continue integrating the curriculum into its broader diversity, equity, and inclusion efforts.

Hackett said it was ultimately the district’s, not parents’, responsibility “to develop a curriculum for all kids that may or may not align with a parents’ beliefs about how we should do it.”

The “Serious Talks” curriculum has been in development at Bowman Elementary School since 2010 and widely used by its faculty since 2016, according to a report prepared by Hackett’s office. Teachers at the Harrington and Estabrook elementary schools have integrated parts of the curriculum into their classrooms, and administrators are working to incorporate parts of the curriculum districtwide, according to Hackett.

The curriculum “teaches students about the diversity of our world, the value each person brings, how to look critically at bias and prejudice, how to understand historic and present-day examples of power, privilege, and oppression,” according to Hackett’s report.

The petition, posted July 11 by an anonymous Change.org user, this week had amassed around 1,700 signatures.

It alleges that the curriculum contains content inappropriate for young children, excludes families with “diverse ethnic, cultural, and religious backgrounds,” and was “quietly piloted a year ago without discussions with parents.”

Ammie Jensen, a mother with three children in Lexington schools, said her youngest child was “having an identity crisis” after a lesson on gender norms.

Jensen said the curriculum does not consider the possibility that young people can eschew gender norms without questioning their gender identity — that girls “can be tomboys,” as she put it.

She said the program is creating “great confusion in gender identity,” which will “cause more of a mental health crisis than the pandemic and separating them from all the other children would.”

The petition accurately notes that there is no way for families to opt out of the curriculum.

Hackett, the superintendent, said in her report that the district’s commitment to diversity is integrated into all its lessons.

Speaking at the School Committee meeting, Hackett said the district has always been transparent about its use of the curriculum and emphasis on diversity, equity, and inclusion, but there is a difference “between transparency and agreement” with the parent community.

“This is not new, this has been around before I ever got here,” she said.

Rina Mazor, a teacher at Lexington High School, said she has seen the school’s culture become more accepting over her more than 16 years working there, partly because of the district’s emphasis on diversity.

“Our students learn to care for themselves and others, while celebrating their differences,” Mazor said.

Shannon Davis, a mother who has had a son in the district for eight years, noted that the curriculum covers issues beyond gender identity and sexuality, including “being a child of immigrants, having two dads, or living with your grandparents.”

“You can’t just remove one section of ‘Serious Talks,’ because that’s not fair,” she said.

The district is currently working to expand and standardize its diversity, equity, and inclusion curriculum, with goals to implement 12-16 lessons for pre-K through fifth grade students by the 2025-2026 school year, officials said.