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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

To think "half your age plus seven" is a massive pile of nonsense?

370 replies

TransportNerd · 01/07/2026 08:07

Mumsnet seems to take a very dim view of age gap relationships, far more so than I think the general population does. I've seen plenty of age gap relationships work just fine.

Every single time they're discussed here, though, someone wheels out the "rule" that you shouldn't date someone younger than half your age plus seven years.

People treat it like it's absolutely set in stone, and that breaking this "rule" is some sort of disgusting taboo. I've even seen someone argue it should be enshrined in law, with penalties for those who break it.

Personally, I've always thought it was complete nonsense. It was simply something in a French novel in the early 1900s. It doesn't really take anything important into account, and ignores the principle that consenting adults can do what they like.

Quite apart from anything else, why is it plus seven? Why not five, eight or ten? I'm sure it's only seven because that's a number that's had mystic significance since ancient times. Not a good basis for making laws!

Anyway:

YABU - yes, it's a rule and shouldn't be broken
YANBU - it's a big pile of nonsense and doesn't mean anything

OP posts:
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IcedPurple · 07/07/2026 13:00

Then you have films like The Wolf of Wall Street. Leonardo di Caprio is 15 years older than Margot Robbie, who played his wife. But in real life the characters were about the same age.

Laurmolonlabe · 07/07/2026 12:57

coocoocachoop · 07/07/2026 12:49

Completely off topic but I watched the film adaptation of Rebecca the other day and it infuriated me they removed the age gap, it is such a fundamental aspect of the novel. Her lack of maturity, the power imbalance, her desire to ‘be grown up’ for Maxim despite the fact he likely picked her due to her naivety in contrast the more assured, mature Rebecca. The one time a spotlight can shine on an age gap and they shied away from it.

Agree, they often do it in Jane Eyre as well, which complete changes the dynamic.

IcedPurple · 07/07/2026 12:54

coocoocachoop · 07/07/2026 12:49

Completely off topic but I watched the film adaptation of Rebecca the other day and it infuriated me they removed the age gap, it is such a fundamental aspect of the novel. Her lack of maturity, the power imbalance, her desire to ‘be grown up’ for Maxim despite the fact he likely picked her due to her naivety in contrast the more assured, mature Rebecca. The one time a spotlight can shine on an age gap and they shied away from it.

You mean the NF one with Lily James? Yes I agree. Generally I hate gratuitous age gaps in TV and film (and it's always the man who is older!) but in this particular case having Maxim as a handsome man only slightly older than the heroine made no sense. As you say, her naivete and the power imbalance is an essential part of the story.

coocoocachoop · 07/07/2026 12:49

Laurmolonlabe · 07/07/2026 12:26

Sounds pretty random, my only problem with age gaps is that you have different frames of reference-TV, films, music,etc.

Completely off topic but I watched the film adaptation of Rebecca the other day and it infuriated me they removed the age gap, it is such a fundamental aspect of the novel. Her lack of maturity, the power imbalance, her desire to ‘be grown up’ for Maxim despite the fact he likely picked her due to her naivety in contrast the more assured, mature Rebecca. The one time a spotlight can shine on an age gap and they shied away from it.

Laurmolonlabe · 07/07/2026 12:26

Sounds pretty random, my only problem with age gaps is that you have different frames of reference-TV, films, music,etc.

OneFineDay22 · 06/07/2026 21:21

kkloo · 06/07/2026 20:20

When that is the case it often makes it worse, not better.

Immature 16 year old boys will still have raging hormones, so they're immature but have more strength, more independence and the sexual drive of an older teenager etc.

Yes exactly this. Girls may act more grown up, but they’re not grown up. Boys may have an immature sense of humour or some other superficial appearance of being immature, but they can be seeking a more adult relationship than a girl their own age, let alone a younger girl.

kkloo · 06/07/2026 20:20

Ladygodalmighty · 06/07/2026 18:32

If the 13 yo is female and the 16 yo is male, then they are probably at the same maturity level 🤔

When that is the case it often makes it worse, not better.

Immature 16 year old boys will still have raging hormones, so they're immature but have more strength, more independence and the sexual drive of an older teenager etc.

Housebashing · 06/07/2026 20:12

IcedPurple · 06/07/2026 20:08

From what I've read, there is some difference in maturity levels between boys and girls, but it amounts to maybe a few years at most, and levels off once they reach adulthood. Definitely doesn't mean that a 19 year old girl is at the same level of 'maturity' as a 40 year old man! I'd think very little of that man if it was. I'd think very little of him anyway.

But you have to ask yourself why have you read that?
Who wrote it? What was their motivation?
as I say, I have firsthand experience on a daily basis
And if the expectations are the same of a boy, then the maturity is the same.

IcedPurple · 06/07/2026 20:08

coocoocachoop · 06/07/2026 19:57

I also hugely question the boys mature later than girls tosh. Feels to me like it suits men a little too conveniently, they’re off the hook for being ‘immature’, they can be impulsive, immoral, lazy at home because the poor mites can’t help their underdeveloped brains. While 18 year old girls are just SO mature, they get those nubile youthful bodies but it’s totally acceptable for the old man to shag her as she acts like a proper grown up.

How often I’ve read stories of females regretting some of their earlier dalliances that I highly suspect they were manipulated into and felt compelled to do to demonstrate their grown up ness.

When I’ve read about the decision making part of the brain not being fully developed until 25, I’ve never heard it discussed in a different context between men and women. If there was, I highly suspect it would be environmental and that shouldn’t be something we’re encouraging.

From what I've read, there is some difference in maturity levels between boys and girls, but it amounts to maybe a few years at most, and levels off once they reach adulthood. Definitely doesn't mean that a 19 year old girl is at the same level of 'maturity' as a 40 year old man! I'd think very little of that man if it was. I'd think very little of him anyway.

coocoocachoop · 06/07/2026 19:57

I also hugely question the boys mature later than girls tosh. Feels to me like it suits men a little too conveniently, they’re off the hook for being ‘immature’, they can be impulsive, immoral, lazy at home because the poor mites can’t help their underdeveloped brains. While 18 year old girls are just SO mature, they get those nubile youthful bodies but it’s totally acceptable for the old man to shag her as she acts like a proper grown up.

How often I’ve read stories of females regretting some of their earlier dalliances that I highly suspect they were manipulated into and felt compelled to do to demonstrate their grown up ness.

When I’ve read about the decision making part of the brain not being fully developed until 25, I’ve never heard it discussed in a different context between men and women. If there was, I highly suspect it would be environmental and that shouldn’t be something we’re encouraging.

HaveYouFedTheFish · 06/07/2026 19:36

Housebashing · 06/07/2026 19:23

I’ve raised teenage boys and teenage girls and I’m sorry I don’t agree with that at all.
All this nonsense about girls mature more than boys serves a particular narrative.
Just because it’s repeated consistently doesn’t make it true

I agree - I have two of each and they're all different and tbh mature in different areas at different times. Social and emotional maturity isn't just one thing, there are plenty of aspects that don't always mature at the same rate.

Boys stay impulsive longer, and their executive planning skills seem to mature later, ime, but that isn't a reason to encourage them to date impulsive younger girls who are similarly poor at planning and time management!

In terms of self assurance, confidence and being comfortable with and having faith in themselves/ self esteem I don't think there's any indication either girls or boys achieve that earlier than the opposite sex as an average.

HaveYouFedTheFish · 06/07/2026 19:30

OneFineDay22 · 06/07/2026 18:40

Girls mature faster than boys, and they may act more “grown up” but you can guarantee a 16 year old boy would feel more ready for a sexual relationship than a 13 year old girl. Aside from the possibility of the older child pressuring the younger child in this way, no form of contraception is 100% effective, and it would be ridiculously irresponsible to risk getting pregnant at 13 years old. Lots of children think they’re ready, and that shows how immature they are.

Exactly, and aside from the three year difference in maturity being incredibly dubious and just someone's random opinion, what % of 16 year old boys will be happy to wait three years until their girlfriend is 16 and they are 19!

Housebashing · 06/07/2026 19:23

Ladygodalmighty · 06/07/2026 18:32

If the 13 yo is female and the 16 yo is male, then they are probably at the same maturity level 🤔

I’ve raised teenage boys and teenage girls and I’m sorry I don’t agree with that at all.
All this nonsense about girls mature more than boys serves a particular narrative.
Just because it’s repeated consistently doesn’t make it true

DrCoconut · 06/07/2026 19:15

My grandmother always said no more than 4 years between you, doesn't matter who is older. She got that from her mother who got it from her mother etc. My ex was 29 and I was 18 when we met. At the time it seemed exciting and I was flattered because I had been mercilessly bullied through school about my appearance. Looking back he obviously targeted me as someone he could manipulate. Plus it was a way to legally have sex with a teenager if you consider that angle. Not OK and my parents didn't like it but what do you know when you're that age and had an extremely sheltered upbringing?

OneFineDay22 · 06/07/2026 18:40

Ladygodalmighty · 06/07/2026 18:32

If the 13 yo is female and the 16 yo is male, then they are probably at the same maturity level 🤔

Girls mature faster than boys, and they may act more “grown up” but you can guarantee a 16 year old boy would feel more ready for a sexual relationship than a 13 year old girl. Aside from the possibility of the older child pressuring the younger child in this way, no form of contraception is 100% effective, and it would be ridiculously irresponsible to risk getting pregnant at 13 years old. Lots of children think they’re ready, and that shows how immature they are.

Ladygodalmighty · 06/07/2026 18:32

If the 13 yo is female and the 16 yo is male, then they are probably at the same maturity level 🤔

IcedPurple · 06/07/2026 17:28

ProBonoPublico · 06/07/2026 17:27

I don't think most men consider maturity to be a particularly attractive characteristic, and particularly not in comparison to the physical attraction of a 20 year old body compared to that of a 40 year old.

Yes, that's why any young woman who believes that her much older man considers her 'so mature for her age' is deluding herself.

ProBonoPublico · 06/07/2026 17:27

IcedPurple · 06/07/2026 12:22

100% this.

Or maybe by the woman girl herself.

If the man was seeking maturity in a woman, he'd go for someone his own age. It's precisely the lack of maturity that attracts men to much younger women, delusions to the contrary aside.

I don't think most men consider maturity to be a particularly attractive characteristic, and particularly not in comparison to the physical attraction of a 20 year old body compared to that of a 40 year old.

IcedPurple · 06/07/2026 12:22

Housebashing · 06/07/2026 04:43

Ive never met a mature 20 year old who was deemed mature by anyone but the man wanting to fuck her

Edited

100% this.

Or maybe by the woman girl herself.

If the man was seeking maturity in a woman, he'd go for someone his own age. It's precisely the lack of maturity that attracts men to much younger women, delusions to the contrary aside.

ProBonoPublico · 06/07/2026 12:18

PenelopeJoanSterling · 05/07/2026 23:03

i much prefer needlework than football

"to", not "than".

OneFineDay22 · 06/07/2026 10:04

PlayingDevilsAdvocateisinteresting · 06/07/2026 04:43

I agree with you @Dizzydrizzy, I have never heard of that "rule" before either!

I also think that when it comes to age gap relationships, each one - if there needs to be any judgement at all - should be judged individually. I don't think that there is a natural law that governs all age gap relationships!

I have been married twice, the first time I was under 20 years old, and he was 4 years older than me, his friends teased him that he was a baby snatcher! My next, and present husband, is almost 8 years older than me, but we started going out when I was 32 and he was almost 40. Which I believe is a perfectly reasonable age gap, but if we had met and started going out when I was 12, and he was almost 20, many people would have called him a paedophile.

So, I am actually interested to know, whether anyone thinks of a particular number of years that would make a difference in ages turn from just being an accepted norm, to then becoming an age gap that is worthy of a damning judgement?

The thread is not about specific age gaps, the point is that a formula has been created to help guide people in what would be acceptable depending on the age - so the gap has to change. Your husband at 20 would have been able to date a 17 year old at the youngest. At 40, the rule here would say he could date a 27 year old - which you were well over that at 32. As others have said, the rule is more for younger people as over 30, most people think you’re definitely an adult. But, again, as you get much older, I wouldn’t want to date a man in his 60s at my age, and would think it was pretty weird if I met a couple with a 40-45 year age gap where the oldest was elderly, even if the youngest was well over 30.

OneFineDay22 · 06/07/2026 09:59

Housebashing · 06/07/2026 04:43

Ive never met a mature 20 year old who was deemed mature by anyone but the man wanting to fuck her

Edited

I have met young people who I think are mature for their age - but it doesn’t give me any desire to enter into a relationship with them. I see them as a separate generation, not a peer. I’m not so ageist to think a younger person has nothing they could teach me. But at most I would think a friendship or even sort of mentor relationship might develop naturally. But romantic? Hmm… I think it’s possible, but I think it’s really extraordinarily rare for two people with such a gap to genuinely connect like that as equals and in the vast majority of these cases it is a problematic dynamic that I have no desire to “normalise”. The happy few will just have to deal with judgements of others, since they are adults and they know full well what they’re getting into. I’m sure they can handle it.

coocoocachoop · 06/07/2026 08:01

PenelopeJoanSterling · 06/07/2026 02:18

it just seems odd that you can vote, join the military, and so on yet somehow if you fall for an older person suddenly your relationship is wrong, yet even same age relationships can and do fall apart so its like what happened society ?

Yes you can join the military, but do you know what you can’t do? Get into a relationship with someone in your chain of command due to the power imbalance among other things (whatever the age) you’re comparing apples and pears, no one is saying an 18 year old isn’t mature enough for a relationship at all. It’s about appropriate relationships.

kkloo · 06/07/2026 05:35

PlayingDevilsAdvocateisinteresting · 06/07/2026 04:43

I agree with you @Dizzydrizzy, I have never heard of that "rule" before either!

I also think that when it comes to age gap relationships, each one - if there needs to be any judgement at all - should be judged individually. I don't think that there is a natural law that governs all age gap relationships!

I have been married twice, the first time I was under 20 years old, and he was 4 years older than me, his friends teased him that he was a baby snatcher! My next, and present husband, is almost 8 years older than me, but we started going out when I was 32 and he was almost 40. Which I believe is a perfectly reasonable age gap, but if we had met and started going out when I was 12, and he was almost 20, many people would have called him a paedophile.

So, I am actually interested to know, whether anyone thinks of a particular number of years that would make a difference in ages turn from just being an accepted norm, to then becoming an age gap that is worthy of a damning judgement?

we started going out when I was 32 and he was almost 40. Which I believe is a perfectly reasonable age gap, but if we had met and started going out when I was 12, and he was almost 20, many people would have called him a paedophile.

What a weird comment to make.
Well yes obviously they would have, and he would have been one.
It's not in any way the same as a 32 and 40 year old.

Housebashing · 06/07/2026 04:43

TransportNerd · 01/07/2026 08:17

I think that's quite patronising to the many sorted and mature twenty-somethings out there.

Ive never met a mature 20 year old who was deemed mature by anyone but the man wanting to fuck her