Over the last few months, lawmakers have sought — not always successfully — to use the singular “they” when introducing nonbinary constituents who have appeared to testify. The elected officials have listened to tutorials on the difference between sexual orientation and gender identity (the former is who you go to bed with, the latter is who you go to bed as); to pleas for compassion from parents who have learned to refer to their children as “my kid” rather than “son” or “daughter”; and to why being called by binary pronouns feels, as Kayden Reff (they/them), 15, of Bethesda, Md., put it in testimony read by their mother, “as though ice is being poured down my back.”

“I’ve always been a liberal Democrat; it’s not like these issues are foreign to me,” said State Representative Michael Winkler (he/him), 68, of Vernon, Conn., who attended a hearing on gender-neutral identification state documents this spring. “But I’m still capable of being educated.”

Some of the antipathy toward nonbinary identities may reflect a generational divide. Over a third of Americans now in their teens and early 20s know someone who uses gender-neutral pronouns, according to a recent survey by Pew Research — more than people in their later 20s and 30s, double the number of those in their 40s, and triple the number of those in their 50s and 60s. Sixty percent of the teenagers surveyed told Pew that forms asking about a person’s gender should include options other than “man” and “woman.”

“Possibly it’s an age issue,” said Jocelyn Doane (she/her), 39, a longtime advocate for progressive causes in Hawaii who struggled with whether to support the gender-neutral license bill in her state. “I want to respect their challenges, but the use of ‘their’ for a single person is making me crazy.”

Objections to the bills have also been raised by social conservatives, like State Senator J.B. Jennings (he/him) of Maryland, who made a distinction in public comments between transgender people who transition from male to female or vice versa, and those who identify as nonbinary. “They’re either going one way or the other, they’re not stuck in the middle,” he said. Mr. Jennings suggested that the license would be inaccurate if it listed a gender other than male or female. His argument was echoed by the California Family Council when that state became the first to adopt gender-neutral documents as law in 2017: “It advances a falsehood that being male or female or no gender at all is a choice each person must make, not a fact to celebrate and accept,” said Jonathan Keller, the group’s president.