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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:
gingerninja · 25/02/2026 19:37

Sorry also wanted to add that a lot of praise can also feel like pressure to a teen. It can make it feel like an impossible standard to maintain and like your only worth linked to ‘success’ this was a huge surprise to me as like you I thought I was doing the right thing heaping on praise but after a lot of reflecting and listening I’m now aware of how it can feel to a teen.

BunnyLake · 25/02/2026 19:41

There’s an old joke that I’ll paraphrase for you.

Full set of Encyclopaedia Brittanica for sale. No longer needed, as son says he knows everything.

TakeALookAtTheseSwatches · 25/02/2026 19:49

It probably is just something he'll grow out of, but not all of them do. I've had to distance myself from a friend because her boyfriend (who seems to be around every single time we meet up) knows absolutely everything about everything and will cut you off mid sentence to tell you you're wrong (even though 99% of the time you're not) and will play devil's advocate about absolutely everything. It is exhausting and highly irritating, I don't know how people live with men like this.

TwoBigNoisyBoys · 25/02/2026 19:49

NamingNoNames · 24/02/2026 10:40

"When I was a boy of fourteen, my father was so ignorant I could hardly stand to have the old man around. But when I got to be twenty-one, I was astonished at how much the old man had learned in seven years."
Mark Twain

My father told me that one. My father wasn't ignorant but he was an arrogant smartarse.

@NamingNoNames i came on to say the exact same thing!

OP, my son was exactly the same between 14-17 ish…he’s 20 now and although he can still be a bit like it, on the whole he listens more and he’s much, much easier to talk to (and cope with!) now, so I agree with many others that it’s a common phase for 15 year old boys! My stepson is exactly the same, and it drives my DP mad…but he’s been like it since he was about 5 (he’s 15 now) so I think it may be his personality rather than a phase 😂

Buzyizzy217 · 25/02/2026 19:50

He’s 15, a teenager. He’ll be fine. Teenagers are a different species to us.

Spiritedlight · 25/02/2026 19:53

Piglet89 · 25/02/2026 19:31

Totally depends on his personality whether it’d crush his confidence.

@Spiritedlightwould the short sharp shock of failing mocks help or hinder?

Kids these days are way too mollycoddled by parents for too long. If he thinks he knows better, just let him get on with it, I say. I honestly cannot be hooped with this kind of crap.

I don't know. But it feels weird letting him fail to teach him a lesson. It goes against my maternal instinct.

OP posts:
WonderingWanda · 25/02/2026 19:56

Have taught teenagers for 25 years and am the proud owner of my very own teenage experts at present. It is very normal and common. Teenagers are naturally over confident about their own knowledge, abilities and experience. They don't have the benefit of experience and no real understanding of all the things they don't know. They are trying to be grown ups and some of them do it badly and rudely. Take no notice of it. With ds we tend to gently take the piss. Say things like "How on earth did I manage to survive for 40 plus years without you explaining things to me.

PoeticEnding · 25/02/2026 20:01

It is important for a boy to show he has knowledge and skills to be a part of society, so his behaviour is normal. This is often expressed in an irritating manner. He is trying to emulate men he sees who are assertive, knowledgeable and skilled.

Keeping correcting him when he is wrong and praising when right. He won't show he understands those corrections, but inside he will acknowledge and grow.

Boys often try to minimise the effort required to do things whereas we teach girls to value outcomes that often need excessive effort or time. Remind him that "hard work beats talent, when talent doesn't work." There are lots of people as bright as your DS they will be hiding how much they are really working to get better grades than others who don't work as hard.

Don't try to leave him to fail in the hope he will recognise his mistakes, boys need our best advice to flourish, just like girls.

Carry on with your high expectations, caring parenting and remember to joke and laugh along the way.

Good luck

FattyMallow · 25/02/2026 20:03

He's a spoiled kid and the reason he's dismissing facts coming from parents (the most valued individuals in a humans psyche), could be, is because he lacked attention at earlier stage of his childhood and made do with whatever means were available at his disposal (Internet, TV, school mates and teachers) without having a concept of the difference between facts and spin/ half truths/fuction. Nevertheless living in your house up to the age when he pays rent, bills and food he will listen to everything that his parents teach and advise. Otherwise he's not a law abiding citizen and no court will ever take his side when Parents are fulfilling their duty and he's obstructing them.

I'd take away the telephone, WiFi and TV until he behaves reasonably.

Rake care of yourself, hope this is just a stage.

Walkaround · 25/02/2026 20:07

Spiritedlight · 25/02/2026 19:53

I don't know. But it feels weird letting him fail to teach him a lesson. It goes against my maternal instinct.

It’s not letting him fail, it’s letting him learn from his mistakes.

Womaninhouse17 · 25/02/2026 20:08

NoFiller · 24/02/2026 10:09

Your husband is very knowledgeable about astrology?

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

😆😅 I suppose it's possible to be knowledgeable about that sort of nonsense, but what would be the point?

BreadstickBurglar · 25/02/2026 20:15

Is what the school is asking for reasonable/likely to help, and does he need to improve his grades? Or is he in fact doing well despite only doing 1 x 30 min whatever it is per week? I only ask because I had a similar experience but in your DS position. My mum went on and on about how I wasn’t working hard enough or extending myself enough during GCSEs, whether that was based on something the school had suggested or just a standard she’d made up I don’t know, but it was fairly corrosive. I did really well in my GCSEs even if I wasn’t reading Dickens in my spare time or writing an extra bit of coursework for no earthly reason. I think she unfortunately thought the best way to express love at this period was through chivvying, but it just made me feel that I wasn’t good enough.

Obviously if he isn’t doing the required coursework etc this doesn’t apply.

Mtlso · 25/02/2026 20:18

I would send an email to the Head of Year, if I were you. If you don’t have their email address, send it to the school’s main email and it’ll be forwarded on. Sounds like he needs a kick up the bum and thinks he’s fine just coasting. You sound like you’re being perfectly reasonable in how you and your husband are talking to him. Not all parents are this supportive. If the HOY knows this, he could be put on report until his conduct and attitude improves, that means the minimum expected, that you don’t just want the quality, but the quantity too. If he finishes easily, has he rushed it, is his handwriting poor? Marks can be taken off for handwriting which obscures an answer. If he finishes easily, then independent study and doing past papers would help. Hormones are nuts at this age so you sound like you’re handling him really well, but there’s honestly not much time left between now and exam time. It must be frustrating to see how smart he is and just not applying himself. If you actually calculate the number of lessons, there isn’t long at all. This is why a lot of schools start GCSEs in Y9.

Hope that helps, OP xx

Caniweartheseones · 25/02/2026 20:18

Not sure if this is useful but my son is like this. Determinedly his own way since toddlerhood no matter what but very personable much of the time. A nice but difficult person (11 years) who has been diagnosed recently with ADHD. What a relief for the whole family! There is a reason, it makes so much sense and there are multiple treatments. He is also relieved because sometimes he annoys himself too and treatment makes his social life much easier.

likeafishneedsabike · 25/02/2026 20:19

OH, the mighty knowledge and experience of the mid teen boy. We all just have to bow to the superiority of this brain.
Luckily mine can be funny too otherwise I would defenestrate him.

Piglet89 · 25/02/2026 20:20

likeafishneedsabike · 25/02/2026 20:19

OH, the mighty knowledge and experience of the mid teen boy. We all just have to bow to the superiority of this brain.
Luckily mine can be funny too otherwise I would defenestrate him.

🤣 mine is only 6.5 ATM: do they all get like this?! How will I cope?

likeafishneedsabike · 25/02/2026 20:23

Piglet89 · 25/02/2026 20:20

🤣 mine is only 6.5 ATM: do they all get like this?! How will I cope?

Actually the DS who is like this was also like it at 6.5. You’re already conditioned for the hormonal, taller version!

Pistachiocake · 25/02/2026 20:38

The old saying about get hold of a teenager while they still know everything! It's very normal for them to challenge their parents, all my friends and family who have teenagers say things just like you, and the older ones say let it just pass, because they are like big toddlers.

LT1233 · 25/02/2026 20:59

This is my son (17), I'm pretty sure he's autistic tbh - I have another autistic son who was diagnosed at 22 months, and the 17yo is much 'more' autistic. Funnily enough my husband is very knowledgeable about astrology, space, science etc too and the 17yo often tries to out-knowledge him when he really hasn't got much of a clue. He got humbled a bit during his year 10 mocks when he went from high flying to grade 3's and 4's (got 8's in the end because I staged an intervention) but he'll still argue that black is white and he's VERY affected by online spaces that tap into young boys (incel culture etc). In my experience, lack of empathy drives a lot of this but my sons overriding issue is that he has to WIN at everything, if he doesn't it absolutely kills him, hence he just talks himself up to being billy big bollocks constantly, to overcompensate for the fact that ironically and sadly, he has no social skills, no real friends, no hobbies and is generally the opposite of winning. The only thing I can do is try and engage him in as much conversation as possible and then mediate on his opinions versus the truth in a very gentle but as multi-dimensional as possible way. It's like explaining things to a toddler and it's very consuming tbh.

Moonlightfrog · 25/02/2026 20:59

My dd was exactly the same at that age….and still is at the age of 22 😬.

I got to the point where I just let her do as she wishes because she knew better than anyone else and was far more intelligent than me. I never checked what work she was doing towards GCSE’s or A levels because if I dared to comment I would be reminded of my lack of intelligence. My dd was diagnosed with Aspergers at the age of 4, she struggled hugely socially but was teachers pet. It sounds mean but I can see why no one wanted to be her friend 😬.

Anyways she breezed through GCSE’s, A levels and Uni and is now back home. She is slowly realising that intelligence isn’t everything and that life’s pretty hard. She’s also realising that sometimes she isn’t right.

HearHareHere · 25/02/2026 21:04

I’m reminded of that old adage which I’ll paraphrase: “when I was a teenager, my parents knew nothing. Now I’ve grown up, it’s amazing how much they’ve learned!” 😁

Imasurvivour · 25/02/2026 21:06

Hi op, those years can be quite awful for parents. I’ve been through it twice. The one thing that children often struggle with is connection. This is especially so with parents.
I found that giving choices worked really well. If my kids wanted to do something, instead of saying outright no I would say - you need to stay at home and do your studying. It would get answered with a no. I would then explain what life for them would be like if they always did what they wanted to do and what life would be if they thought about their future and what can be achieved.
I told them true life scenarios, such as falling in the wrong crowd, petty crime, police involvement, having a low paid job instead of a career I would let them make up their own mind.
They are learning to become adults and need to make adult choices. When the emotion is taken out of the situation (parents vs child) you may see a different side of your son.

Ruthdpl · 25/02/2026 21:08

“I suggest you encourage your son to pursue a trade if his grades are bad. Also, if he’s arguing about things he has no knowledge of he will completely fail at University as no one will put up with his BS”

This is actually spot on. Up until 2 years ago when I retired I was a Uni Lecturer and taught many an undergraduate like this. Some didn’t do the reading, thought they knew it all (despite little or no life/work experience) and would argue back if they received a poor mark. Consequently they didn’t learn anything because their barriers were too big. That is until they failed an assignment or exam, which focussed their attention wonderfully.
it sounds as though your boy needs a bit of tough love. You don’t want to be paying £9k a year for him to continue messing about.

Lunaticmess · 25/02/2026 21:19

Yes, we had this. During GCSE years, it became a bit unbearable and DS was late diagnosed as high-functioning autistic. Not saying that this is your issue but maybe worth considering if there are any other indicators of odd behaviour that can't be passed off as hormones or cockiness. DS flew under the radar for ages. Did amazingly well at primary school, but things went downhill in high school. He became condescending, unwilling to do any homework, and did the absolute bare minimum for GCSEs but somehow did ok for college. A-Levles are a very different story,and I'm concerned that failing might be the only way to get it through to him that he will need to do some work if he wants to get somewhere. It's tricky though, because he can't concentrate because he's ND. I suspect he might have ADHD too.

Kerrie1973 · 25/02/2026 21:26

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.

I called my son 'Google' at the same age, because he knew everything.

Thankfully at 21, he is less of a twat now. 😂