“People always say the longer it is, the sluttier it is,” said Esther Adina Sash, a 30-year-old mother of two from Flatbush.

Specifically, she’s referring to the sheitels, or wigs, that she and other married Orthodox women wear as mandated by Jewish law, so as to not entice men who aren’t their husbands. Now a heated debate is brewing over hair that some in the community view as being too sexy.

Traditionally, sheitels reflect what is considered modest: shoulder-length or shorter — almost Jackie Kennedy-esque — and synthetic, which is seen as more humble than wearing human hair. (Prices can range from a few hundred dollars to as much as $5,000 for a 28-inch, waist-grazing wig of European hair.)

On her Instagram account (@flatbushgirl), which has some 38,000 followers, Sash regularly posts photos of herself in wigs that cascade and curl down her back, prompting hateful comments. “Go drown yourself in a lake — you’re negatively influencing young girls,” she recalled one reading.

She’s been criticized by rabbis, including one who challenged her to cut her wig as a good example to others — and to receive an “astronomical” spiritual reward.

She didn’t take the bait.

“I was laughing that he would think hair length has a connection to spirituality,” said Sash, who crusades for women’s issues in the Jewish community and is running for district leader in the 45th Assembly District. Although, she admitted, “The wig is a very charged item.”

Last month, The Voice of Lakewood, a Jewish paper in New Jersey, banned wig makers’ ads that show photos of hair, according to a memo sent to advertisers and obtained by The Post. It comes on the heels of a nasty dustup that took place last fall when digital fliers were anonymously e-mailed to area wig makers, reading in part: “Dear Jewish Women, how badly are you trying to look like a prostitute? How important is it for you to slap G-d in the face?!”

“It was a scare tactic. ‘Let’s scare a bunch of people,’” said Menucha Kaminsky, a wig stylist in Brooklyn.

And it seems to be working.

“Some customers tell me we have to cut it short enough ‘so I don’t get in trouble,’” said Galit Lavi, owner of BH Wigs in Borough Park. She has seen a recent uptick in this happening with young mothers who have kids ­entering school.

“Of course it’s hard for them — it’s a sacrifice. They like the long­er hair,” said Lavi. But “some rabbis question it. I hear it all the time.”

Gitty Berger, a 33-year-old makeup artist from the Orthodox community of Jackson, NJ, has sheitels of varying lengths and styles — but saves her longest ones for outside her neighborhood.

“If you’re seen in a local pizza shop wearing a long wig, you’ll be talked about,” said the mother of four. “People will go to [school or synagogue] administrations about you and you and your husband will be getting phone calls.”

Another woman named Esther — a 34-year-old in New Jersey who asked that her last name be withheld for privacy reasons — felt the sting of rejection based on her coiffure a few years ago when she and her husband tried to buy a house in a Lakewood development. “I was turned away because my wig was too long,” she said. “We were told that we will scare off the crowd [and] they need to sell the rest of the lots.”

But some young Orthodox women are increasingly more defiant of societal expectations — even though they don’t wish to disobey religious convention.

“I’m an Orthodox woman and I want to adhere to my traditions, but why do I have to look like I’m from ‘Fiddler on the Roof’?” asked Mindy Meyer, a 28-year-old lawyer from Flatbush.

“It’s hotter and sexier to have long hair,” she added. “I’m not trying to conform. I don’t care what people think about my long wigs because, as long as I’m doing what I’m supposed to be doing, G-d is the ultimate judge.”