Recently, I bumped into an old school friend and — both being Jewish mothers — the catch up conversation inevitably involved an audit of our growing families.

Fortunately, I vaguely remembered that this woman’s son was a rising star in corporate finance and so provided the cue for her to glow about his stellar career. (I got at least ten bars of If you could see him now.)

However, when I shmoozed that this boy was quite the catch, his mother told me that her son had already been caught — by a gorgeous young teacher, no less, who was utterly devoted to him and who was adored by all the family, including my friend — a significant coup considering the territorial reflex of the Jewish matriarch.

Yet, something in her pleated brow telegraphed a big, fat “but”. Which she duly expressed. In three big, fat words: “She’s not Jewish.”

Frankly, I was surprised she was that bothered. After all, here was a woman whose own family weren’t remotely religious (think: “Should I have the lobster or the gammon?”).

Yet the idea of her son marrying out was profoundly upsetting. Equally, the possibility of rejecting a girl who made her son so happy, was a source of great distress. We parted with words that have walked with me since. “I suppose he’s old enough to work it out.”

Or is he? As a famous rabbi once told a congregant who came to him about his son’s non-Jewish girlfriend, “How old is the boy? Twenty-five? You’re 30 years too late asking this question.”

But how do parents — those who worry about the prospect of their children marrying out — prevent such a match coming to pass?

And in post-millennial, all inclusive, 21st-century Britain, should it even be a conversation we should be having with our children?

Some may even find it offensive to raise the question. After all, one in 10 couples is now ethnically mixed, according to the Office of National Statistics.

What’s more, where once some families mourned and sat shivah when a child chose a non-Jewish spouse, today, ex-communication has almost always been exchanged for, at the very least, grudging acknowledgment.

I conducted a straw poll among friends and acquaintances; one mum told me: “I just want my children to be happy. Marrying someone Jewish isn’t as important as them having a happy life together.”

The latest research shows that marriage between Jews and non-Jews is at a record high of 26 per cent.

Yet it remains a perverse irony that even some of the most unreligious and assimilated Jews still want their children to marry Jewish.

As one young man — currently squiring a non-Jewish girl — responded to his dismayed father: “Why, all of a sudden, are you so Jewish, when it comes to whom I marry ? You spend most Saturday afternoons at the football and haven’t been to shul in 20 years?”

So for those of us who would mind our children marrying out — and yes, I declare my hand — is there such a thing as a pre-emptive strike?

Emotionally, many parents like myself believe (and desperately hope) that having a heritage steeped in practising Judaism will ensure the desire to “do Jewish” will remain deeply ingrained in their choices.

As Ephraim Mirvis, the Chief Rabbi, has said: “Levels of Jewish attachment, religious observance and continuity, directly correlate with ‘endogamy’ — marrying in.”

Not that it stops me making little digs (not always appreciated) at my lot.

For example, when I recently attempted to make challah, the rich, yeasty scent wafting through the house was intoxicating. “Ah,” I told my boys. “You won’t get wonderful smells like that if you marry out.”

Though when I withdrew two hardened rocks from the oven they retorted that they wouldn’t have to break their teeth on home-made challah either.

One friend, however, takes a far more hard-line approach. She incorporates her wishes for her children to marry in, into the blessing she gives them on a Friday night.

She says (and I’m quoting verbatim from the message she sent to me): “May Hashem bless and protect you, may he shine his light upon you and may you always be a good Jewish girl/boy and marry someone Jewish.” And her children’s reaction? “They hate me saying the last bit as they think it is embarrassing but I’ve told them that they will reach the end of their line of Jewish heritage if they marry out.”

Rabbi Benji Silverstone, who through his involvement with Jewish education group Aish, has worked with countless students over the years, says the challenge for parents who are not religious is explaining why children shouldn’t marry out .

“They may tell their kids, ‘I won’t have Jewish grandchildren if you do it.’ The response may be, ‘So what? You don’t even practise yourself.’

“So parents have to know why it is important to be Jewish. I take the view of Doron Kornbluth, the author of best-seller Why Be Jewish, who points out that any cross-cultural marriage has a fair chance of not working out. The differences can eventually become a challenge.”

The other approach, suggests Rabbi Silverstone is “check it out before you chuck it out” — that is, look at Judaism to see if there is anything in it that is worth giving up the relationship.

“I knew of a Jewish student who was going out with a non-Jewish boy — but my wife and I still invited them for Shabbat meals.

“Her parents were furious with us for seeming to endorse the relationship, so I said to her mum and dad ‘come back in 18 months. If they are still going out, you are right to have a go at me’.

“The couple came a few times, then the girl started coming without the boyfriend. Other families started to invite her and she started to reconnect with her Judaism. Eventually, she saw the life she wanted and gave the boy up.”

Not everyone will agree with this plan. Some may not even have the appetite to try. Others may find it offensive. Ultimately, it is a personal decision.

Although, perhaps, when it comes down to it, the warm smell of freshly baked challah may well be the place to start.