Meet the Other Phone. Flexible and made to last.

Meet the Other Phone.
Flexible and made to last.

Buy now

Please or to access all these features

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:
BunnyLake · 24/02/2026 13:16

It’s a phase. I went through it and my kids did. We think we know everything at that age and people with decades more life experience know nothing.

meemeemammy · 24/02/2026 13:16

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'm sorry, but this just made me laugh out loud ( sat in Tesco cafe on my own- thinking of the Dad reading the horoscopes) I'm really sorry.

mumonthehill · 24/02/2026 13:17

Most used phrase here at that age was, we agree to disagree!! I think Ds thought I was very stupid and he was apparently always right. It does change, infact it is surprising how suddenly you are asked for advice and support. I was all knowing when it came to uni applications, buying a house, interview hints. You just have to laugh it off really.

meemeemammy · 24/02/2026 13:20

I do think this is an age thing, and I'm the centre of the universe type of thing. Their brains are still very much developing to see / hear others point of views. My 15 year old daughter is sometimes like this and comes out with all sorts! Doesn't listen, doesn't wear a coat when it's raining, promises me she's ready when she's not. I think it's just teenagers. Hopefully his grades will be ok

Jellycatspyjamas · 24/02/2026 13:22

At 15 he’s working things out for himself - his views, opinions, ethics and needs to be able to express these. As long as he’s not disrespectful I’d let him get on with it. I don’t need my kids to be right, have all the information or to agree with me - they’re learning, and trial and error is all part of that.

My DS can wax lyrical on something for ages, and I’m happy to listen even if I think he’s wrong, I disagree or whatever, the important thing is he wants to communicate with me. If it’s not dangerous or harmful, I’ll let him crack on.

Muffinmam · 24/02/2026 13:22

He doesn’t sound smart - he sounds narcissistic.

An intelligent person doesn’t argue about things they know nothing about.

My brother was/is incredibly intelligent. He was gifted as a child and coasted through school without any effort.

He argued about things he knew about and as an adult he is extremely well read and now works in a STEM field.

The problem with gifted children is they can burn out after highschool. They grow up knowing they were the smartest in their entire school and never had to try. At University they are often not the smartest and need to actually show up to lectures or they will fail.

There’s also the possibility that a person can be so intelligent they can feel ostracised from their peers and suffer terrible mental health.

I don’t think your son is at any risk of either of the above scenarios.

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.

As a parent it is your responsibility to prepare your children for society’s expectations and part of that is social intercourse. Without social skills he will fail to establish a social network at University or in any workplace which will very much limit his career options.

Teenagerantruns · 24/02/2026 13:23

Absolutely nightmare age. I would leave school work up to him. You cant force him.
If hes disrespectful at home just ignore there is really no winning an argument with a teenager. Just let the low level annoying things go.

GasPanic · 24/02/2026 13:26

I think he has to learn from his own mistakes. The problem is that at a young age that can be extremely costly. But to be fair you can retake exams if you fail.

Part of the problem at that age is that it is hard to understand what you don't know. The problem is that the publicly accessible stuff is normally at a very reduced level and it can be easy to fool yourself into thinking you believe you understand it, but the backing behind it is often very complex.

I remember getting to university the first time, and the thing that impressed me most was just how much knowledge there is out there. If you go into a library and look at the rows and rows and racks and racks of journals, it becomes quickly apparent that it is impossible to know everything, and even the stuff that you do want to know and specialise in is very complex and takes time to understand.

Re the more specific interests he has like astronomy, where does he get his information from ? Normally the web, but what sources ? If he for example goes on some of the more accessible sites for astronomy that's great, but may not be testing him in the way he needs to be tested. There are sites and channels out there that dig into issues in much greater detail and hopefully are capable of humbling him somewhat.

He doesn't sound like he is far away from being ready to go to Uni, at least at an academic level if not at a life experience level and when he gets there he will be able to focus all his skills on something a lot more challenging.

In the meantime, and in the few final years you have left together at home, maybe it is best to try to engineer situations where rather than your interaction with him being confrontational and a test of "who knows the most" on a subject try to orient them more towards shared experiences where you can listen together.

Captcha4903 · 24/02/2026 13:29

I thought I knew everything at that age. I had never failed at anything...

Spiritedlight · 24/02/2026 13:37

Muffinmam · 24/02/2026 13:22

He doesn’t sound smart - he sounds narcissistic.

An intelligent person doesn’t argue about things they know nothing about.

My brother was/is incredibly intelligent. He was gifted as a child and coasted through school without any effort.

He argued about things he knew about and as an adult he is extremely well read and now works in a STEM field.

The problem with gifted children is they can burn out after highschool. They grow up knowing they were the smartest in their entire school and never had to try. At University they are often not the smartest and need to actually show up to lectures or they will fail.

There’s also the possibility that a person can be so intelligent they can feel ostracised from their peers and suffer terrible mental health.

I don’t think your son is at any risk of either of the above scenarios.

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.

As a parent it is your responsibility to prepare your children for society’s expectations and part of that is social intercourse. Without social skills he will fail to establish a social network at University or in any workplace which will very much limit his career options.

With all due respect, that's a ridiculous jump. It is not narcissism. Being a “know-it-all” is a behaviour. Narcissism is a personality pattern. Nor is he gifted. And he has social skills; I'm talking strictly about his relationship with us.

OP posts:
pinkyredrose · 24/02/2026 13:38

CustardySergeant · 24/02/2026 12:57

Yes, she said so in her post at 10.22.

I missed it!

HelpMeUnpickThis · 24/02/2026 13:39

Spiritedlight · 24/02/2026 13:04

Thank you for the advice and the feedback. It's sobering re: harsh tone - that said, I am VERY aware of it, he knows I'm aware of it, and it's countered by a ton of praise, love and unabashed pride in who he is. But my own traumas and upbringing certainly contributed to my directness and sharpness - it's no excuse, but it's something I am very aware of and constantly try to work on.

Thank you for the important reminder - my relationship with kids is of the utmost importance.

Hi @Spiritedlight

I am NOT trying to pick on you but please do whatever you can to sort out your own childhood / upbringing issues so that you don’t pass on the trauma to your son.

You say you are aware that your background affects how you speak / interact with your son. If so - then do something about it.

Don’t pass the trauma down.

LeedsLoiner · 24/02/2026 13:40

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.

Sounds like he's perfectly qualified !

lizzielizard · 24/02/2026 13:40

“When I was a boy of 14, my father was so ignorant I could hardly stand to have the old man around. But when I got to be 21, I was astonished at how much the old man had learned in seven years.”
Mark Twain

SomersetBrie · 24/02/2026 13:41

Muffinmam · 24/02/2026 13:22

He doesn’t sound smart - he sounds narcissistic.

An intelligent person doesn’t argue about things they know nothing about.

My brother was/is incredibly intelligent. He was gifted as a child and coasted through school without any effort.

He argued about things he knew about and as an adult he is extremely well read and now works in a STEM field.

The problem with gifted children is they can burn out after highschool. They grow up knowing they were the smartest in their entire school and never had to try. At University they are often not the smartest and need to actually show up to lectures or they will fail.

There’s also the possibility that a person can be so intelligent they can feel ostracised from their peers and suffer terrible mental health.

I don’t think your son is at any risk of either of the above scenarios.

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.

As a parent it is your responsibility to prepare your children for society’s expectations and part of that is social intercourse. Without social skills he will fail to establish a social network at University or in any workplace which will very much limit his career options.

I'm guessing you've never meet a teenager?

Franpie · 24/02/2026 13:42

There is absolutely nothing that my teenagers don’t know. Me and DH on the other hand are old and stupid and don’t know anything about anything.

I just silently repeat the mantra in my head “this too shall pass”.

Lemonade2011 · 24/02/2026 13:52

Ah the joy of teenage boys, I have 2 older boys (24 & 21) who also thought they knew it all and just wanted to do their own thing a not listen. It was a trying time!! ( it does pass) and currently have a 15 year old - 16 soon and a 14 year old who in 15 in June. So your post resonates. My son is lovely but he can just be a moody arrogant little so and so at times.

I don’t do the harsh tone as soon as you do they’ve switched off. We just explain you treat people with respect even if you think you do ‘know it all’ and we are doing the exams this year and passing means choice for s5 and 6 so he needs to step it up. It’s hard work though!!! They can be so arsey sometimes it’s hard to not get angry.

my older 2 are doing well though so I hold on to the fact that it will all work out in the end….

RobinEllacotStrike · 24/02/2026 14:01

Just want to share this Mark Twain quote with you OP - hang in there:

“When I was a boy of 14, my father was so ignorant I could hardly stand to have the old man around. But when I got to be 21, I was astonished at how much the old man had learned in seven years.”
Mark Twain

My know it all is now 18 & things are getting much better

Ormally · 24/02/2026 14:02

15 year olds don't want to be 'edited' by you (and, to an extent, vice-versa too).
They recognise the importance of being 'edited' by teachers and information, but resent it a lot of the time. At the right times, it will light a fire of determination and enthusiasm rather than heart sink and grind. I suspect this is the early stages of a few years of it.

Haven't really trodden a consistent path with it, but instead of having a struggle of wills and how right you are or not, some phrases have been more successful: "Ok, but you do see why I keep trying to guide you into doing this?" is one. "Do you think (he) is really being respectful by saying that?" was another, about a character being arsey in a film. Not always a great result, but some result.

NamingNoNames · 24/02/2026 14:03

@RobinEllacotStrike , that quote has already been posted on page 2.

ApplebyArrows · 24/02/2026 14:04

To be honest I think think the school are being completely unrealistic in requiring this sort of self-study at this age. Directed homework tasks are generally educationally effective; "spend an hour reading your notes" is not.

Violinist64 · 24/02/2026 14:05

This is about the worst stage with teenage boys. Girls tend to to be at their worst in their early teens when their hormones run riot but it seems to mostly take the form of tears, drama and flouncing with them. Boys are at their worst in the mid-teens, as you are experiencing. The know-it-all phase, accompanied with a loud voice and deafness to any reasoned argument is classic and extremely wearing. The good news is that they do outgrow this phase. When one of my sons was seventeen, he was all set to join the communist party. My mother was horrified but I knew he would outgrow it - l called him our resident red. He was not bothered about the USA banning anyone with communist leanings from entering the country but when he found out that Singapore, where we have some close family members, takes an equally dim view of communism, he felt that family came first and his principles became watered down out of necessity.

DysmalRadius · 24/02/2026 14:08

I have also pointed out, to some of the more emphatic teens that I have encountered, that it's easy to know everything with the internet in your pocket. When my brain was at its most plastic, you had much more limited access to information about anything.

If I wanted to know if frogs can cough when I was 14, I had to hope that there would be a documentary on frogs that covered it sometime when I was at home in the next few months. Now, you can have the world's leading frog expert telling you everything you want to know in seconds! 😁

SomersetBrie · 24/02/2026 14:09

DysmalRadius · 24/02/2026 14:08

I have also pointed out, to some of the more emphatic teens that I have encountered, that it's easy to know everything with the internet in your pocket. When my brain was at its most plastic, you had much more limited access to information about anything.

If I wanted to know if frogs can cough when I was 14, I had to hope that there would be a documentary on frogs that covered it sometime when I was at home in the next few months. Now, you can have the world's leading frog expert telling you everything you want to know in seconds! 😁

The world's leading frog expert usually being a teenage boy 😁

Simplesbest · 24/02/2026 14:10

My 15 yo went through this. I got very bored very quickly especially when he thought he was the cleverest person in the house yet was failing all his exams dismally. I just regularly burst his bubble in the end. Stuck to facts and kept bringing it back to what he had actually achieved so far in his life vs what he imagined he had achieved. He passed through it and we laugh about it now but he was so far up his own arse it was embarrassing.

Swipe left for the next trending thread