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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:
UnctuousUnicorns · 24/02/2026 10:56

Having had three teenaged DDs in my time (youngest is 16) I can assure you that it's not just a boy thing; girls can be just as big a know-it-all pain in the arse at times. It's part of adolescence but yes, it's a chore at the time. My older two are now 26 and 25, and both pleasant, hard working human beings, so hang on in there. It does get better.

MoreMaths · 24/02/2026 11:00

I often said to DH that I wished I was as clever or knew as much as a 15/16 year old. 😂

I think it's a very natural phase linked with growing up, hormones, identity and often friendship groups. They are beginning to establish themselves and navigate the world as a young adult whilst still needing the boundaries and security of being a child - and that can be hard for them to articulate in what we might see as a more mature fashion.

I read "Get Out of My Life, But First Could You Drive Me & Cheryl to the Mall?" by Anthony Wolf and would recommend it. Lots of helpful advice about picking your battles, trying to understand things from a teen perspective and dealing with common issues.

SatsumaDog · 24/02/2026 11:02

Yep, teenagers can be a bit like this. I just told mine that the ball was in their court. I was doing my bit, but if they chose to ignore my advice (re studying) then it was their choice. They are the ones who have to live with the results. For the rest of their lives. Universities generally only care about the grades on the piece of paper, for the first selection criteria. Obviously there are interviews etc for some, but you won’t get past the first gate if your grades aren’t good enough. Get that bit wrong through arrogance and inability to listen to parents and teachers then don’t come looking for sympathy from me. I’ll be able to do f all for you if you fuck up! Sometimes they need to hear it like it is.

BlackeyedSusan · 24/02/2026 11:02

It'll be really surprising how much you will both learn by the time he is 25!

This too shall pass.

In the meantime: nudge. Why do you think that? Do other sources have a different opinion? Etc.

Don't butt heads over it. It's really not worth it.

School work: Praise what he does do. gentle approach gets more results.

Send him links, text, talk in the car.

Good luck.

KaleidoscopeSmile · 24/02/2026 11:02

ThePerfectWeekender · 24/02/2026 10:15

Astronomy or astrology? No wonder DS is mocking DH.

Some other smartarse has already said this. Why not just assume that she meant astronomy?

Sharpcorners621 · 24/02/2026 11:03

Spiritedlight
About the defence mechanism thing; I think it is real and exists in the evolving teenage brain. I remember reading that experiments have proven that adolescents literally interpret tone of voice and expression as being more negative than they are in reality. It’s a preservation adaptation I think from way back when we lived in tribes designed to kick in when they leave the safety of the group? A bit like toddlers being fussy about foods once they can move and explore.

So although it’s infuriating, your timing and approach and tone need to be right.

Pick your battles, use humour, don’t be permanently on his case. Reserve proper talks for when you are on drives or engaged doing something else, Don’t confront him head on as it were! And make sure you spend positive moments with him too. Invent errands if you have to where you spend some time together and end it with a treat of some sort.

And of course the more avoidant, defensive and pretending to be on top of things they are, the more usual it is for them to be drifting, rebelling or having difficulties… so you are right to be concerned.

But you have to turn the responsibility over to him. Emphasise that he has choices. And that you believe in his competence and abilities. That you will offer back up support in whatever area he needs, he only has to ask, but it’s down to him now. And that you will be genuinely interested to know how he will use his time and all of these positive assets?

He has to learn self motivation at some point and the earlier the better.

Tell him that you love him so much that you want him to make the most of his considerable talents, so you will be checking in again about his academics over Easter or whenever.

Be serene and positive (even if you feel the opposite) because they need us to be steady when they are going through so much change. Don’t appear to be permanently anxious if you want them to share their worries with you. Get on with your own life and be a good role model.

Ignore the bluster such as contradicting your dh. That’s normal rejection of parental beliefs in order to establish his own identity and it’s healthy albeit a bit daft.

As for the know it all cockiness, we always took that as a sign that our dc needed more challenges and responsibility to test them.

One year we were so exasperated by our teen daughters’ negativity and superiority on holiday that we arranged through friends for them to help out with a youth volunteering programme where they were the only Brits and they had little money and few language skills and they had no choice but to make the best of it for a few days. They were much more pleasant to be around after that!

Blueartichoke · 24/02/2026 11:03

My Ds is 15 and can be like this, he won’t listen sometimes and thinks he knows best. We explain to him our reasoning behind what we are saying to him when he doesn’t listen but sometimes we just let him figure things out for himself, if he gets stuff wrong hopefully he learns from it. His mocks haven’t been great due to lack of effort and we have talked this through with him and when he feels like we are ‘getting at him’ we try and explain we just want to support him the best we can. I think that’s the key, support as this is a difficult period for them on the brink of GCSE’s and making decisions for the future.

BlackeyedSusan · 24/02/2026 11:11

Spiritedlight · 24/02/2026 10:15

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

What do you enjoy about him? Focus on that. It makes the rest a bit more bearable. They are still really cute when they are asleep! And not talking

Exam prep cost me a bloody fortune in rewards, but we had some really enjoyable meals out together and had chance to chat. A buffet restaurant have the opportunity for him to get up and get more stuff. Yours might like something different.

lizziebuck · 24/02/2026 11:14

Haven’t you ever heard the saying ‘employ a teenager whilst they still know everything’?

it is a very well known phenomenon. Not overly helpful and I never really went through it, but you are not alone.

Ireallycantthinkofagoodone · 24/02/2026 11:16

Spiritedlight · 24/02/2026 10:14

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

Did you mean ASTRONOMY rather than ASTROLOGY?

Quine0nline · 24/02/2026 11:17

This is Mumsnet - your husband is wrong, now what is the question?

It was Mark twain who said
When I was 18 I was surprised how ignorant my father was.
When I was 21 I was surprised how much he had learned in the intervening years.

thanks2 · 24/02/2026 11:17

My son used to drive me insane with his know it all at that age - I think it’s about them being low in confidence and internally they are boosting their own confidence by convincing themselves they know it all!!

I do think though it was helpful for my son not to do so well in his mocks - he did ok but was a mark or two off being able to stay at his grammar school. It really shook him that he did not do as well as he expected and he knuckled down in a mad panic and got all 9s and 8s much to even his surprise. He thought he was reading the wrong results.

better to do badly in mocks then feign confidence in mocks and crash in the final exams

BlackeyedSusan · 24/02/2026 11:21

Spiritedlight · 24/02/2026 10:17

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

They are extremely sensitive. They see anger where there is fear or other emotions. Their brains are undergoing a rewire. It's shit for them too.

You are doing some things right.(Maybe more)You sound a bit tetchy in some of your replies on here so maybe he perceives this as well, even if you don't intend it. They are quick to take offence even when you think you are talking normally. You need to be very very careful.

Maybe it's just a phase and you are not particularly doing anything wrong. They are tricky. Watched teens talk back to head of year at school.

Questions such as how do you think I feel when... are often better at bringing about change.

They need lots of love and praise.

Perfect28 · 24/02/2026 11:22

Pretty sure you just have a teenager.

thanks2 · 24/02/2026 11:22

One thing I would say is focus on maths and English and any subjects he needs as a prerequisite for what a levels he wants to do. Look at his schools a levels. It would be better to get a 7 or higher for maths and English and say a 5 for a language … then to get 6 for all three subjects as an example

MyDeftDuck · 24/02/2026 11:26

Ask him if he speaks to his teachers in such a condescending manner for a start.
Following on from that, back off from any conversation other than the basic household questions around meals, bed linen changing, sports kit etc.

Pr1mr0se · 24/02/2026 11:27

There is a phrase 'ask a teenage whilst they still know everything'. So you are not alone.

However do you have any relatives or good friends who your son respects who could have a word with him? If they talk to him about study and demonstrate disappointment in his approach, could that have a positive effect on his attitude?

His bravado could be insecurity or he could really know that he's not doing as well as he'd like but doesn't know what to do. Sometimes 'more study' isn't the only answer to fix this sort of thing in teenagers, it can be a symptom of other things going on such as fitting into his peer group etc

Teenagers are going through a lot of changes and expected to be adults for all sorts of things when really they don't have the maturity to cope.

I think your husband has a point - the results of the mocks could fix it if they are not as good as he'd hoped and may galvanise study.

It may help if you and your husband have times in the day when you are all 'studying' something and quiet. That approach helped in our house. So no music, no TV whilst he is revising so that you are all 'in it together'.

MajorProcrastination · 24/02/2026 11:28

Hormones! Testing boundaries! Feeling like an adult when you're still a child!

He's not the first and he won't be the last but that doesn't mean it's not challenging to navigate as a parent who wants to do the best for their child.

Girls can be like this too, thinking of my step daughter (e.g. when she asked me if I was sure my birthday was in a certain month as she'd always thought it was the month before. Yes. I am aware of my own birth date and it's been the same every year). We'd roll our eyes and be calm and pleasant about it as any debate would blow right up.

There's an element of rising above and letting them making some mistakes and decisions but also always being clear that everyone in the household deserves respect and love and time and space and support. Not in a "you must respect your father" way but in a "you can expect us to treat you with love and respect but we are also deserving of the same" way.

I'm with your DH, let him make the errors and learn some lessons. Does your DC go to parents evenings with you? I've found it useful with my youngest to have those conversations with the teachers and him at the same time so the teachers can see that we're on the same page and my son can see it's not his parents being enemies, we're just trying to support him and give him the framework to do the best he can do. He's bright but he's also testing these boundaries at the moment and while he's been funny and clever, as he gets bigger and older it can lean too far into being mean (to his bigger, older, quieter, stronger brother) and being too cheeky and chopsy in school with teachers (he doesn't get in trouble, it's stuff like asking what the teacher's having for their tea).

It's best that he learns the impact of thinking he knows best and not doing the prep work NOW rather than in Uni like my cocky brother did.

I'm not saying to let him get away with acting like he knows everything and doing no homework but talk to him in an adult way "you're old enough to take responsibility for your revision, school have advised this so that's up to you to do that work when it fits in for you".

But when he's quoting bollocks, call him out on it. "What's your source?" "that's interesting, I didn't know that, where did you find that out?" and chat about the dangers of misinformation.

Apologynotaccepted · 24/02/2026 11:32

Teacher here and I can concur that a lot of teenage boys are now like this. It's a legacy of the 'everything is communication' bollocks and the eroding of how we expect young people to speak to adults . Then we let it all crash down on their heads when they go to college. It's disgraceful on our part.

PJ98 · 24/02/2026 11:33

Leave him to fail his mocks.

My friend has a son who kept saying "rest time is so important when you're revising" and "my teachers say that you need to take loads of rest breaks" and then didn't revise at all because he was so focused on using his revision "breaks" as an excuse to play on his xbox. He got really low marks in most GCSEs which was of course everyone else's fault.

DysmalRadius · 24/02/2026 11:37

Op, this is honestly not intended to be a 'gotcha' but in this thread you made a mistake in your OP, and when a poster pointed it out, your initial response was chippy and dismissive without actually reading what they wrote or checking what you had written.

Does that sound like your son at all?

I am only pointing this out because the number 1 thing that annoys me in my kids is when they demonstrate the behaviour traits I like least about myself.

NamingNoNames · 24/02/2026 11:45

... the number 1 thing that annoys me in my kids is when they demonstrate the behaviour traits I like least about myself.

With bells on.

sociableintrovert123 · 24/02/2026 11:46

Sorry OP I don’t have any advice but wanted to say my DS age 15 is exactly the same. He thinks he’s an expert on everything and is extremely confident. I put up with it to a certain extent at home although I do point out that he sounds like a bit of a know it all at times. I worry how this attitude will translate in the workplace.
@murphysI needed to read that today! I’m finding my age 15 DS so difficult! I thought parenting would be easier at this stage.

FlowerFairyDaisy · 24/02/2026 11:50

What you have been doing isn't working and isn't changing anything so it's a pointless exercise.

Just let him get on with his life in his own way.

I do understand the frustration but they find their own way.

You obviously meant astronomy (space) not astrology (star signs).

onelumporthree · 24/02/2026 11:52

You can only learn from your mistakes if you are allowed to make them.

Your DH is right - let him get on with it and if he doesn't do as well in his GCSEs as he thinks he will, perhaps that will be the kick up the arse he needs.