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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:
Member984815 · 24/02/2026 10:26

He's just a normal 15 Yr old , he'll soon realise he doesn't know everything and wise up . For now just let him give his opinions and fully listen , he's just expressing himself . Teenagers get such a hard time these days its a tough time to navigate even tougher now with social media and other pressures.

chergar · 24/02/2026 10:27

This is common at that age - my son went through it as well, we just asked that if he had a different opinion to someone to be respectful in how he argues his point. I think it is great that our children feel they can question what they are being told, especially when they form arguments to back up their case.
I am not saying this is you OP but some parents do have the attitude of “I know what’s best, don’t argue back” which isn’t helpful and hinders their child’s critical thinking and reasoning skills that they need to develop for the real world.

Christmasinmecar · 24/02/2026 10:29

NoFiller · 24/02/2026 10:09

Your husband is very knowledgeable about astrology?

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

Did OP mean astromony but said astrology instead? 🙄

Mangelwurzelfortea · 24/02/2026 10:32

I've got a know-it-all son too. He is 16 but it's the same. It's annoying that he knows everything much better than I ever will, but he'll grow out of it!

He also 'managed my expectations' about his GCSEs, did well but not as well as he was capable of doing (he's very clever but did the minimum of work) and will be annoyed when his sister gets better grades than he did in a year's time. But he has 'locked in' for his A-levels (and actually does seem to be studying a lot) so that's a good thing anyway.

Christmasinmecar · 24/02/2026 10:35

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 read OP as saying h is very knowledge about the subject but s quotes back at h usually talking bollocks, it's that's talking random rubbish not h.
I'm sorry if I read that incorrectly OP.

murphys · 24/02/2026 10:35

Christmasinmecar · 24/02/2026 10:29

Did OP mean astromony but said astrology instead? 🙄

Yes and we have moved on from that now.

SomersetBrie · 24/02/2026 10:38

My 15 year old knew everything. It was so annoying as I used to really like talking to him about stuff when he was younger, he was interested in so many things. We used to chat about news and politics during dinner - how smug I was at how knowledgeable and informed he was!
Then suddenly he knew everything and it was no longer fun talking to him!
He also likes to be right, so it wasn't ok to disagree with him, he wasn't happy til you came around to his view.
He's 16 now and it's still quite bad but he is better at accepting different views.

I am looking forward to when he's stops knowing everything as the interesting person is still there underneath.

Lavender14 · 24/02/2026 10:40

I agree with the pp who says to try to work with him on the fact its fine to have different opinions to others, but that he needs to be careful in how he communicates it because it can come across as disrespectful and that will start to affect his relationships if he's not careful. Plus it means he's not bringing anyone along with him if they get annoyed by the way he's phrasing things.

Any lads I've known who have acted in this way were either autistic and it came across as disrespectful but actually they were just being very matter of fact and their opinion was just very concrete. Or it's been a confidence issue and they're feeling very unsure in themselves and are effectively trying to fake it till they make it.

So I would work on confidence and self esteem with him as well as clear information on how phrasing and tone matters. But I do think op that unless you're suspecting ND that sometimes you have to pick your battles and decide if its something to let slide and internally roll your eyes or if it's a hill to die on. I think maintaining an open relationship through the next few years and sticking with them is what brings them back round on the other side of it all.

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.

NorfolkandBad · 24/02/2026 10:40

DD was like that, but was doing well at school so not a big concern, she would make comments about things and then when asked to explain (as part of a conversation, not a confrontation) would effectively reply "it just is". We realised it was her peer group at school who were feeding her this nonsense and now she's a few years older, she's realised the same herself.

thewonderfulmrswatson · 24/02/2026 10:41

I used to tell my children (all 4 are boys) "if you think you know everything you will learn nothing" my second son who will be 20 this year used to be like that.
It was always a case of using facts over feelings with him when he was been that way.
Feelings count for a lot amd were always taken on board but they don't overrule facts. Example "you can feel you're doing well science but fact is your grades say different"
He isn't like that now. I can't remember when it stopped but it did.

TheSandgroper · 24/02/2026 10:43

DH has been a 15 year old boy. You haven’t. They are different from us. If you have a good egg for a DH, take your lead from him.

I will say that with DD, I drank more gin that year as I prepared dinner.

2026problemsandDDcanbeone · 24/02/2026 10:44

My DD was (and still is, to an extent) like this, if you don’t agree with her everything turns into a debate.

I used to think “whatever, life will teach her” but now I wish I had given her more of a pushback during her teenage years, it would probably have saved a few frustrations down the line.

Saying that, maybe your son is onto something regarding astrology and space………..

BauhausOfEliott · 24/02/2026 10:44

Honestly, I think your son sounds like a very normal teenager. I appreciate that it's massively annoying, but I don't think he's at all unusual to be going through an 'I know best' phase.

PinkyFlamingo · 24/02/2026 10:46

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 on earth do you mean by that?!!

HelpMeUnpickThis · 24/02/2026 10:48

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

@Spiritedlight

I too would find the arrogant back chat very trying.

I agree with PP that rather than make it a debate I would just detach - grey rock, change subject etc. I wouldn’t get entangled in debates that wind me up or where I know there is a big, demonstrable difference in knowledge/experience and the other party is not open to listening or learning. I just don't have the patience for it. Same applies for adults too BTW.

I would really struggle with the lack of academic “focus”. I have put that in quotations because he might be focused but not appreciate being micro managed. Or not able to see cause and effect due to lack of experience and immaturity. For this I’d suggest you pick your hard line conversations and be less vocal about the rest. Sometimes people only learn through consequences.

Just reading your posts I do think you sound quite negative. You have repeatedly said “this is the worst stage of parenting”. Gently, your DS does not owe you a specific parenting journey. He is trying to figure himself out and let’s be honest, he doesn't really know how to do this. Your job is to support not be an oppressive critic. Try to reframe your thoughts (and perhaps words?) about how you are finding this stage of parenting. It’s quite clear you are not enjoying it. Maybe he is picking up on this low key disdain?

What I DO think you urgently need to work on is your critical or “harsh” tone, as mentioned by you. This is absolutely horrific to live with. Ask me how I know.

It’s ok to be ambitious for your son but living with someone who is constantly nit picking, correcting, giving unsolicited advice, telling you are wrong is a recipe to a distanced relationship as soon as independence is gained and years of therapy to unpick the resentment. Speaking from
lived experience.

Good luck.

UnctuousUnicorns · 24/02/2026 10:50

PinkyFlamingo · 24/02/2026 10:46

What on earth do you mean by that?!!

It's okay; I had to think about it for a few moments. My brain clearly hasn't engaged yet today. 😅

Happyjoe · 24/02/2026 10:52

Friend of mines son was rude and know it all like this - but it lasted until he finished university. When he came home full time to live, he was know it all with his mum, rude, didn't listen..no matter what mum said or what she did, she was wrong and he knew better. But, although later than some, he grew out of it within a year. He's quite a nice lad now, balanced, no longer condescending and helpful to his mum. She stopped trying to correct him or take the bait, just walked away from him when he was rude and took away his audience.

I guess ride it out. If he really will not listen to advice or want to talk about his future education wise, let him find out the hard way. You can lead a horse to water etc!

HRTQueen · 24/02/2026 10:52

I would often tell ds I had not idea how I got on in life without a teenage son

it was almost everything from driving to politics to how young women experience the world, there was nothing he wasn't an expert on and more knowledgeable about than I was

now he is a few years older the subjects of his expertise have lessened, his friends are very similar

He doesn't yet quite grasp male entitlement but he is aware of the concept of entitlement (more than I was at his age) and self awareness will come with maturity

stickygotstuck · 24/02/2026 10:52

Likely a testosterone surge.
It gives males their arrogance and feelings of superiority. Totally unjustified and they tend to grow out of it if kept in check.

Just keep an eye make sure he does grow out. Contradicting him and pointing out when he's wrong should help.

PPs are right that by 17/18 it seems to pass all being well.

Nofeckingway · 24/02/2026 10:53

This

15 year-old know it all son
Whattodo1610 · 24/02/2026 10:53

He sounds like a normal 15 year old 🤷‍♀️ I agree it’s difficult to live through, but he’s changing from a boy to a man, that’s just how it is. He’s finding his way, they all think they know it all at that age. You need to try to be the bigger adult and just rise above it. It really is just a normal part of growing up 🤷‍♀️

allthingsinmoderation · 24/02/2026 10:55

Ahh the "know it all" phase.
I think its developmentally normal and the positive is the confidence and that can be helpful.
i think the advice to Listen to him,use facts rather than emotions to reason with him and let him find out through experience rather than being told are good ideas.
My daughter went through this phase and recently we discussed it when her son was exibiting similar ideas. My daughter said "you cant put an old head on young shoulders" i spat my tea out and asked of she remembered me saying that to her when she was 15 yrs old ....

Channellingsophistication · 24/02/2026 10:55

I don't think I could tell my DS anything when he was 15 because he knew about everything, or it didn't work like that or that wasn't how life is these days...

I think this stage will pass, my DS is 18 now and he does actually listen and agree with what I say, sometimes anyway.

I think 15 is a difficult age with GCSE's approaching

Jimmyneutronsforehead · 24/02/2026 10:56

Is being a know it all not a rite of passage for most teenagers?

He will grow out of it, or he'll grow into it.

He'll certainly have life experiences that challenge his knowledge and he'll either be humbled or he will learn more and develop better critical thinking skills.