This is no “sensitive area” in Ramallah, Cairo or Tehran, nor some gloomy banlieue outside Paris. We are talking to a quiet, middle-class family living in the centre of contemporary Montpellier, a lively university city and one of the economic hubs of France’s Mediterranean coast. Grandmother Rose is 82, her daughter Valérie, 52, and the two grand-daughters, Lila and Laura, 17 and 10. They all asked for their names to be changed, except Rose. “I shall soon be passing on, so it no longer matters,” she says.

Rose and Valérie are sitting on the sofa, talking. The old lady thinks her daughter is too open about being Jewish. “It’s almost as if you were waving a banner.” “Not at all, Mummy, that’s nonsense. I only say so when the question crops up,” Valérie retorts. But Rose’s fears are not allayed. “If you’re in contact with a lot of people in your daily life, you should be more careful,” she warns.

Le Monde later talks to Valérie and her younger daughter after school, in a café on Place de la Canourgue. Laura is very talkative. “Our teacher asked the class who was a practising Muslim,” she says. “Ten pupils put up their hands. After that he asked who was Catholic and one girl answered, the one from Guatemala. Then the Muslims explained their religious rites.”

“That’s all. He didn’t ask who was Jewish?” her mother inquires. “Well no, he’s very respectful, he’s not going to ask us if we’re Jewish.”

“What do you mean, ‘respectful’? If he’d asked who was Jewish, would you have put your hand up?” Valérie asks. “No way, you’re crazy,” Laura protests. “I don’t want to get beaten up. I’ll never say I’m Jewish.”

“So you don’t tell anyone?” Valérie asks.

“Never have, never will. I don’t want to lose my friends for that. As it is they think I’m spoilt because I have pocket money and I’ve never been spanked, not like them! If on top of all that they found out I was Jewish, I’d be done for.”

Later we listen in on Valérie and Lila on the phone.

“Would you like to talk to the journalist about what you told me?” the former asks.

“What do you mean?”

“Well, you know, about not daring to say you’re Jewish …”

“Oh, Mum. It’s past history,” Lila counters. “I couldn’t care less about being Jewish. I just have Arab friends and I don’t want any problems – that’s all.”

“But what sort of friends are they, if you daren’t admit you’re Jewish?”

Valérie is a writer and leads writing workshops. In her bohemian house in the centre of Montpellier the walls are almost bare, but there is a close-up photograph of an inscription, one name among 76,000 etched into the stone of the Mémorial de la Shoah in Paris. It reads: “Jacob Slod, 1905.” It is the name of her grandfather, Rose’s father, a Polish Jew who fled to France and was later deported.

Of the three generations of women in her family, Valérie is the only one publicly to affirm her Jewishness. She is trapped between two forms of denial: on the one hand by her mother Rose, a hardline atheist, still traumatised by the second world war, who systematically dismisses any mention of being a Jew; and on the other by her own daughters, who face a new form of antisemitism, which affects parts of France’s far-left under the cover of anti-Zionism and generates anonymous bravado on social media. This mixture of factors feeds on the crisis in democracy, the Middle East conflict and age-old stereotypes that all Jews are rich and powerful.

Lila and Laura have grown up with events such as the murder of Ilan Halimi, a young Jewish man who was kidnapped in January 2006 and held for three weeks, during which time he was tortured, leading to his death. In 2012 Mohamed Merah killed four people, including three children, outside a Jewish school in Toulouse. On 7 January Islamist gunmen murdered 12 people at satirical weekly Charlie Hebdo, then two days later an accomplice took hostages at a kosher supermarket in south Paris, killing three straight away and another one during the final assault by the police. A police officer was also killed in associated violence. Until the attack on a synagogue in Copenhagen in February, France was the only western country where its own citizens had killed Jews for being Jewish. In 2015, the year of the 70th anniversary of the liberation of Auschwitz, young French Jews are still afraid to acknowledge the community to which they belong.

A poster by French street artist Combo on the coexistence of religions, pictured near the Arab World Institute in Paris. Notre-Dame cathedral is seen behind. Photograph: Joel Saget/Getty

When Rose put away her father’s belongings in the attic, she marked “Jacques Slod” on the boxes, instead of his real name, out of fear of there may one day be reprisals if it was found. Slod, a shoe-mender, left Poland in 1935, telling everyone that he would never return. Seven years later he was taken back, on the first train into Auschwitz from the internment camp at Drancy, east of Paris.

He had originally set out on his own, deserting his wife and two daughters, Dora and Rodja, respectively aged three and two. Life in Paris was splendid: one repair job was enough to cover the day’s rent on his shop and buy him an evening meal. In 1938 his wife travelled to Paris with Rodja in the hope of persuading her husband to come back. She failed but left Rodja behind. Slod was among the first people to be picked up and held at Drancy in August 1941. He stayed there till March 1942. The Rothschild Foundation rescued Rodja and she went into hiding with a family of farmers at Dourdan, south of Paris.

Then aged nine, Rodja did not know she was Jewish. She could make no sense of all the family drama, nor did she know why her father had been picked up. The family in Dourdan sent her to a school run by Catholic nuns. Madame Boudan decided her name should be Rose and the matter was never raised again. She went to classes to learn the catechism, became a fervent Catholic and decided this religion was “good and just”. Everyone else was preparing for their first communion so she asked the priest if she could, too. His refusal was just as mysterious as everything else in her life: “You mustn’t. If your father comes back he wouldn’t be pleased.”

And Slod did come back. He survived four years in captivity at various camps. Rose went to see him at a reception centre in the 18th arrondissement in Paris. He was distant and told her nothing. After a drink he would occasionally say a little more. She remembers something he repeated over and over, in his halting French: “They were given a bar of soap, they went in the showers and that was it. The others turned on the gas.” He had a number, 28126, tattooed on his arm but he never mentioned the word “Auschwitz”. What was the point in talking about something no one would believe.

Rose’s husband – a dashing accordion player she met in a bar in Belleville when she was working as a seamstress – finally put her in the picture. She was 17, he was 10 years older, a colon from Algeria, a French citizen of Spanish extraction. He was an atheist, though his family were Catholics and antisemitic. He had fought alongside the Allies to oust the Germans, and told Rose all about the camps. Her father was against their marriage, complaining that her beloved was “old and not Jewish”. She did not care. They married, had three children and moved to Montpellier.

The children did not have a Jewish surname, which suited Rose. “I thought it was pointless and dangerous,” she explains. She stuck to this line until her elder son, a militant Maoist, started making “seriously antisemitic” comments, which went much further than just criticising Israel. “As long as Jews are deported like animals, people feel sorrow for them, but once they have their own country no one wants them any longer,” she asserts. She told her son that she was Jewish and so was he. He could not see what it had to do with him.

His sister Valérie, who was nine at the time, found out she was Jewish too. Now that she is an adult she is not practising and disapproves of Israel’s policy on settlements, but feels the need to celebrate Yom Kippur. The fathers of both her daughters are gentiles and she has only managed to persuade the girls into a synagogue a couple of times.

In 2015, young French Jews are still afraid to acknowledge the community to which they belong

Valérie is worried. “If my daughters cover up their origins and if all the remaining Jews do the same, my grandchildren won’t even know they’re Jewish,” she says. “If that happens, the extermination of Europe’s Jews will have succeeded.” Sitting on the sofa at home she turns to her mother and tells her in a loud voice to make sure she can hear: “You see Mummy, not talking about it is as if the Holocaust had achieved its aims.”

Rose is unmoved. She looks tired and downcast. “You didn’t go through what I did,” she retorts. “What good do you get out of being Jewish?”

“I know. Nothing but problems. So you think it’s OK to forget?”

“If need be we must forget,” says Rose. “We’re not going to change humankind. The small peoples will always be sacrificed. It does upset me a bit that the little ones won’t speak out, but they’re right. If it causes so much fuss, it’s better not to talk about it. Particularly if you don’t believe in it. What’s the point in suffering for that?”

In a café on Boulevard des Arceaux, Lila is talking quietly, afraid that the man at the bar wearing a keffiyeh may hear her. “It’s awful,” she says, “I feel guilty about hiding like this. I’m not ashamed to be Jewish … well a bit. But the fear turns into shame.” She says there are times when “we talk about all that – Israel, the Palestinians, Charlie Hebdo, terrorists” at school, and how her “Arab friends” let slip that “the Jews are rich and kill Arabs”. On one occasion, to see what happened, Lila tried speaking out : “Eh! You know I’m Jewish”. They looked at her, then said she must be joking. She let it pass. “Yeah, just joking.” They thought it was funny, Lila says.

Her sister Laura asserts: “God doesn’t exist, because if he did there wouldn’t be terrorists. That much is certain.” Asked what she has in common with a practising Jew, she thinks for a moment: “A practising Jew and me, even if we’re not the same age, even if we’re not acquainted, we’ve been through the same things.”

This article appeared in Guardian Weekly, which incorporates material from Le Monde