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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

15 year-old know it all son

308 replies

Spiritedlight · 24/02/2026 10:00

Hi everyone

I would like to have thoughts on how to handle/progress with son. He's 15, smart, lovely, very opinionated, completely resistant to being told anything and thinks he knows it all.

For example, a discussion about astrology/space etc - whilst DH is very knowledgable, DS will disagree with everything DH says, and quote, frankly, bollocks a lot of the time.

If we talk to him about the school's recommendations for self-study in Year 10 - which I know he's not doing, because I know what they expect - e.g., 2 x 30 mins of going over triple science lessons a week -he will completely tractor over the discussion with comments like, "I'm doing it through homework, it's about quality not quantity (he does the bare minimum), my grades are very good (not as good as he thinks) etc etc". Everything gets brushed off, diminished, he knows best. Always.

It's the oddest, most annoying thing. I've tried to talk to him about it but I don't get anywhere - except that he thinks we are telling him off, which suggests to me this is a defence mechanism. And we are really not telling him off in those moments, we're trying to open up conversation and be supportive about these school years.

I'm worried about his grades and how he's just going to not fulfil his potential. DH thinks let him get on with it and fail mocks etc, so he'll see for himself. But I don't know what to do.

OP posts:
BlueMoonBlueCheese · 24/02/2026 10:03

Sounds like he needs a jolly good listening to.

Spiritedlight · 24/02/2026 10:05

BlueMoonBlueCheese · 24/02/2026 10:03

Sounds like he needs a jolly good listening to.

With respect, that doesn't really help me.

OP posts:
PointlessTrip · 24/02/2026 10:07

Has he always been like this? I have known some boys go through phases of this cockiness. It does seem to pass with maturity. Very tedious to be around though!

NoFiller · 24/02/2026 10:09

Your husband is very knowledgeable about astrology?

Not surprised your son is telling him he’s speaking bollocks.

Toddlerteaplease · 24/02/2026 10:11

PointlessTrip · 24/02/2026 10:07

Has he always been like this? I have known some boys go through phases of this cockiness. It does seem to pass with maturity. Very tedious to be around though!

A friends son is exactly the same. His parents just laughed it off and said he was going to be a politician, but I found annoying and rude.

HelenaWaiting · 24/02/2026 10:11

Spiritedlight · 24/02/2026 10:05

With respect, that doesn't really help me.

We dealt with something similar by dealing solely in facts - what does he want to do next, what grades in what subjects does he need, where is his progress towards those grades. That's all GCSE results are, at the end of the day, just a passport to the next phase. 8s and 9s are nice, but within a very few years, no one will care or even ask what GCSE grades he got. Take the emotion out of it, stick to the facts. Worked for us.

murphys · 24/02/2026 10:12

15 year old boys and generally a bit of a nightmare OP.

The year that my ds was 15, the parents of the whole year were called in to the school at the start of the year. We were told that this could quite possibly be one of the hardest years of parenting due to their age. Hormones, changing bodies, the odd age of not a child and not an adult, so they don't quite know where they fit.

You and dh need to be a team and set good boundries. And then grit your teeth a lot and in a year or so, he will become pretty nice and normal again.

frozendaisy · 24/02/2026 10:13

Yep let him fail his mocks he will have to turn it around if he wants to

at least then you will have lower marks in black and white to suggest perhaps more effort and the teacher’s advice could be listened to

Spiritedlight · 24/02/2026 10:14

NoFiller · 24/02/2026 10:09

Your husband is very knowledgeable about astrology?

Not surprised your son is telling him he’s speaking bollocks.

What kind of comment is this? That's just rude

OP posts:
Spiritedlight · 24/02/2026 10:14

Toddlerteaplease · 24/02/2026 10:11

A friends son is exactly the same. His parents just laughed it off and said he was going to be a politician, but I found annoying and rude.

I find it very rude and annoying and arrogant

OP posts:
Spiritedlight · 24/02/2026 10:14

HelenaWaiting · 24/02/2026 10:11

We dealt with something similar by dealing solely in facts - what does he want to do next, what grades in what subjects does he need, where is his progress towards those grades. That's all GCSE results are, at the end of the day, just a passport to the next phase. 8s and 9s are nice, but within a very few years, no one will care or even ask what GCSE grades he got. Take the emotion out of it, stick to the facts. Worked for us.

That's really good advice, thanks.

OP posts:
ThePerfectWeekender · 24/02/2026 10:15

Astronomy or astrology? No wonder DS is mocking DH.

BlueMoonBlueCheese · 24/02/2026 10:15

Spiritedlight · 24/02/2026 10:05

With respect, that doesn't really help me.

Maybe it was intended to make you reflect.

Why does he think you are telling him off?

Children's communication skills are a reflection of their parents communication skills or lack thereof.
Maybe you don't realise it but the tone you are using is critical, negative etc.
Maybe you never praise him, it's hard for any reader to say with the limited information.
Maybe try and take him for a meal or a walk and talk about the good things in his life and gently try and find out if there is anything worrying him?

Gallowayan · 24/02/2026 10:15

I think your description of this as a "defence mechanism" is pretty accurate. Let's face most 15 year old are not that knowlegable. Not an easy thing to accept so he can't accept it. All you can do is provide him with the tools he needs. Ultimately he might have to fail in order to gain enough insight into his actual level of ability and improve.n

Spiritedlight · 24/02/2026 10:15

murphys · 24/02/2026 10:12

15 year old boys and generally a bit of a nightmare OP.

The year that my ds was 15, the parents of the whole year were called in to the school at the start of the year. We were told that this could quite possibly be one of the hardest years of parenting due to their age. Hormones, changing bodies, the odd age of not a child and not an adult, so they don't quite know where they fit.

You and dh need to be a team and set good boundries. And then grit your teeth a lot and in a year or so, he will become pretty nice and normal again.

Yes, this is, without question, the worst stage of parenting so far. Completely unenjoyable.

OP posts:
Spiritedlight · 24/02/2026 10:17

BlueMoonBlueCheese · 24/02/2026 10:15

Maybe it was intended to make you reflect.

Why does he think you are telling him off?

Children's communication skills are a reflection of their parents communication skills or lack thereof.
Maybe you don't realise it but the tone you are using is critical, negative etc.
Maybe you never praise him, it's hard for any reader to say with the limited information.
Maybe try and take him for a meal or a walk and talk about the good things in his life and gently try and find out if there is anything worrying him?

I don't know how that one sentence of yours could make me reflect, in any way.

That said, your comments here resonate. I do think my tone can be quite harsh sometimes and he points it out and I always apologise. We are very good at 'repair'.

That said, he gets tons of praise and nurturing and we are always talking

OP posts:
jimoine · 24/02/2026 10:17

My DS was like that, but he seems to be growing out of it now (17). They like to test out these behaviours at home with their parents, as a safe place to practise in. I doubt they do it with teachers or other kids’ parents. It’s bloody annoying and very difficult not to react to, especially if all you want is to sit and chat peacefully over dinner.
If my DS continues to justify why the sky is green, I just put my hands up and say yes, of course you’re right, you know everything.

Octavia64 · 24/02/2026 10:19

Firstly, many teenage boys are like this.

arguing with them just feeds it.
focus solely on outcomes. Is he doing as well as he wants to at school? If not then put rewards and consequences in place. If so then ignore as much as possible.

on a separate note I think you have confused astronomy and astrology. Astronomy is the scientific study of stars.
astrology is the belief that the stars impact how we act on earth through our star signs (which stars were in the sky when we were born) and I don’t think anyone really believes in it these days

RappelChoan · 24/02/2026 10:21

He’s immature- all adolescents are immature and your role is to support him as he gains life experience and maturity.

He will alternate between wanting the safety of children and the freedom of adulthood, but it’s a teetering sort of time.

You can be a role model for him of a happy and well balanced adult living a good life. Give him something to aspire to but don’t put him under a microscope of what homework has he done. Show him how to disagree gracefully. Be patient and calm. Keep your boundaries.

Funnys · 24/02/2026 10:21

15 year old boys do know everything, obviously!

My DS1 was like this, not rude, but wouldn't accept any advice about school or exams etc.

We had to leave him to it, for fear of damaging our relationship with him. He had to find his own way and work out that if you don't work you will fails your exams.

He did OK in his GCSE's and A Levels, however did enough to get on a music degree course. It has honestly been the making of him. He is now a lovely young adult with a growing following as an electronic musician.

Hang in there @Spiritedlight, just support him and things will get better

Spiritedlight · 24/02/2026 10:22

I mean astronomy!! I'm so sorry to the poster who I said was rude. I'm running into a meeting but will respond more when out

OP posts:
RosesAndHellebores · 24/02/2026 10:24

@Spiritedlight this too shall pass. At 15 DS would argue the wall was black, not white. We tried hard to deflect the comments but it was a challenging time with little or no listening to other perspectives. He had uncontestable views based on many things: politics, the police, social justice, liberal arts v stem, his headmaster, whether the sun was fucking shining.

He's 31 now, married, expecting a baby and has a PhD. He started to revert to his chilled, sunny self when he was about 22, getting back to base at about 25 when I think the frontal cortex is fully formed. Be glad he has the confidence in his nurture and security at home to kick off at home. At this stage it's all about the export model.

murphys · 24/02/2026 10:24

Spiritedlight · 24/02/2026 10:15

Yes, this is, without question, the worst stage of parenting so far. Completely unenjoyable.

I am not sure there are many that can say they got through parenting a 15 year old boy completely unscathed.

Some will come along and say their 15 year old's were perfect specimens of the human race and they never ever pushed their luck or boundaries. To this I say that they just forgot what is was really like that year.

My ds is very sporty and was in various teams at that age. So the parents from each sport would socialise after events quite often. So there was a big ratio of 15 year old parents in one place at one time. We were definitely not alone in our thinking, and most of the boys played up in one way or another that year.

But they have mostly all turned out fine young men OP. It is just important to lay the ground rules of what is acceptable and what is not.

Sharpcorners621 · 24/02/2026 10:24

BlueMoonBlueCheese · 24/02/2026 10:03

Sounds like he needs a jolly good listening to.

BlueMoonBlueCheese
Why give this pat answer when op has literally just said,

“we are really not telling him off in those moments, we're trying to open up conversation and be supportive”
??

ldnmusic87 · 24/02/2026 10:24

Just leave him to it, he'll learn he's not the smart arse he thinks he is

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