On a morgue slab in Shejaiya in the Gaza Strip a few days ago lay two anonymous children, a boy and a girl. Their bodies could not be identified because their parents, according to Sharif Abdel Kouddous, a journalist for the Nation magazine, were already dead. Israel’s continuing assault on Gaza has claimed hundreds of Palestinian lives and has created 81,000 refugees. I should support it, according to many Zionist opinionators, because I am half Jewish. They tell me that those children had to die so that my future children can be safe. In the end, they say, it’s about blood.

Does it matter what Jews, and people from Jewish backgrounds, say about Gaza? It does when children are being murdered in our names, and in the names of family members for whom we have recently said Kaddish. Jews are better placed than anyone else to articulate a powerful call for ceasefire that does not fall back on the sort of lazy anti-Semitism that seems to the Israeli military to prove its point.

People of Jewish descent have every reason to be hyper-vigilant about anti-Semitic language and it is stupid to pretend that there’s none of it in the global movement for Palestinian freedom. It’s stupid to pretend that nobody ever conflates Jews with Zionists, or labels the Jewish people bloodthirsty and barbarous. And it hurts like hell to hear hoary old words of hate trickling through a movement that is about justice, about freedom, about protecting some of the world’s most persecuted people. It hurts just as much, however, to hear right-wing Israelis tell Jews around the world that the violence is for us, for our ancestors, for our children.

It is not anti-Semitic to suggest that Israel doesn’t get a free pass to kill whoever it likes in order to feel “safe”. It is not anti-Semitic to point out that if what Israel needs to feel “safe” is to pen the Palestinian people in an open prison under military occupation, the state’s definition of safety might warrant some unpacking. And it is not anti-Semitic to say that this so-called war is one in which only one side actually has an army.

It is not hate speech to reiterate the wild disparity in casualties. More than 600 Palestinians have been killed this past week, most of them civilians. Fewer than 30 Israelis have died, and most of them were soldiers. To speak of proportionality is not to call, as at least one silverback columnist has claimed, for “more dead Jews”.

One can mourn loss of life on both sides without condoning further bloodshed. The families of the young Israeli soldiers killed on the front lines of a conflict they didn’t create are grieving, too. That doesn’t change the fact that the casualties are disproportionate. This is a conflict in which no one wants to edge towards saying the word “genocide”, because in this context that is a term so loaded that what’s left of reasoned debate staggers and falls to its knees.

Comparisons to the Holocaust are crass – except when it is Israeli politicians who make them, as the economy minister Naftali Bennett did on CNN, accusing Hamas of “conducting mass self-genocide”. Then the comparisons become obscene. Binyamin Netanyahu’s ministers tell the world that families in Gaza that remain in their homes have nobody but themselves to blame when they are massacred. Ayelet Shaked, of the far-right Jewish Home Party, went further, posting on her Facebook page that the mothers of Palestinian men should “follow their sons [to hell] . . . Nothing would be more just. They should go, as should the physical homes in which they raised the snakes. Otherwise, more little snakes will be raised there.”

This sort of hate speech is not just disturbing – it is disturbed. We must have a compassionate reading of Jewish and Israeli history to understand where that disturbance comes from. Over 20 centuries of faith and survival, the Jewish people have been persecuted, forced into exile, tortured, traumatised, ridiculed, harassed and finally murdered in their millions, and that matters – it still matters, to the children and grandchildren and great-grandchildren of those who survived, including me.

But the abused sometimes go on to abuse others. Countries formed in response to genocide expand their borders with murderous intolerance. People whose communities are bombed and bulldozed fire rockets back. Cycles of violence are comprehensible. That doesn’t mean they are acceptable. That doesn’t mean they can never stop.

Last weekend, hundreds of thousands of men, women and children around the world marched to express their disgust at Israel’s air and ground assault on the Gaza Strip, and among them were swathes of Jews and Israelis. This is one of the few situations in which it makes a difference to stand up and say: not in our name. Not now, not ever again. Being Jewish, or having Jewish roots, doesn’t make you responsible for what is happening in Gaza, but it does mean that your dissent carries that much more weight. Not more weight than the grieving relatives of the families butchered in Shejaiya, but the kind of weight that hangs heavy on the heart, and that comes with the small but palpable risk of upsetting your family.

So here it is. I think my ancestors who were persecuted, tormented and exiled down the centuries for being Jews would be horrified to see what is being done in their name today. Maybe it’s crass to put words in the mouths of your dead relatives, but right-wing hawks have been putting their opinions in the mouths of my dead relatives for weeks, so I think I’m entitled to a say, too.

Because in the end, it is about blood. Not blood as metonym or metaphor, but the actual stuff, wet on the faces of screaming children in Gaza. It’s about blood, and how much more of it will have to be shed before Israel finally feels “safe”, and how long the international community will stand by. The moral basis for Israel’s persecution of the Palestinian people is eroding fast. It is not anti-Semitic to say “not in my name”.

Laurie Penny’s “Unspeakable Things: Sex, Lies and Revolution” is newly published by Bloomsbury (£12.99)