People who always big themselves up..

Your SiL craves praise. Maybe she didn't get much as a child. Maybe she got over much and has discovered the adult world doesn't dish it out as freely. Whatever the reason, its very important to her. So when she self praises she's prompting you to praise her. When she repeats the praise of others she's telling you because it's something that meant a lot to her. She praises your brother because he's an extension of her. Point is, it's probably not about wanting to seem better than you as much as wanting you to tell her how good she is. Unfortunately because its so annoying, it rarely works so she keeps on trying.

people bragging and being arrogant is an odd thing to irritate someone?
surely it's literally one of the most common annoying characteristics?
It's hardly an esoteric personality quirk that has no impact on anyone else, and it's not even as though it's a school mum or near stranger the OP can easily avoid - it's her close family.
that's like saying 'why do you care your brother is always late? seems an odd thing to irritate you?'

Someone being irritating is a very normal thing to be irritated by!

Oh yes people pleasers…. I wonder whether the people they’re supposedly “pleasing” feel pleased!

Yes, or occasionally, completely straight-faced, ‘God, you’re so great, Nigel. You’re so inspiring. I mean DH and I just don’t anything, ever. We phone in sick and slob around watching tv and chainsmoking, occasionally throwing a packet of crisps at the children.’

I think it’s less often that than that the self-described ‘too nice’ are in fact chronic people-pleasers who trade services for ‘friendship’, usually because their self-esteem is too low for them to think other people might just enjoy their company. Which means they bustle around helping and being a shoulder to cry on, all the while secretly resenting the ‘friends’ who take their services for granted. Even though they’re the ones who set up the expectation.

“Yeah, you’ve said before……”, looking bored 🥱

Oh anyone who describes them self as “too nice” (thankfully only on mumsnet!) I always smile. I doubt others would describe said person as “too nice” and I would bet that the “too nice” person makes it very very clear whenever they do do something for someone else that they deserve and must be given profuse thanks and recognition and to remember this wonderful thing!

I honestly don’t know any people like this and some of our friends include successful IT consultants, architects, doctors, headteachers etc. They have all come from very humble (poverty stricken in some cases I think) backgrounds.

The thing they have in common is that they’re all very practical and skilled in manual work too, possibly due to jobs they did before or during their studies (and in one case, since retirement). On first meeting, you would also never expect that they were in these professions either.

I’m wondering if these braggadocio types are more often found in the south east of England, where I’m from? I’ve certainly not experienced it up here in the North/Midlands but I don’t think the pace of life is as pressured - there isn’t so much requirement to keep up with the Jones’s.

As a naturally self deprecating Brit who moved to the US I used to find it very cringy & uncomfortable. Now I'm all for it. Big yourself up, celebrate your small wins. Tell everyone how awesome your husband and kids are. You'll feel a whole lot more positive about life and it's contagious.

The thing I have come to realise op, is that this is a known trait of insecure people. More secure people do not have the need to boast.

I don't big myself up but more and more recently, I've been thinking that I should start.

Being in any way self-deprecating or telling any light-hearted stories about things going tits up for me leads to endlessly embellished tales from family and friends about "Butchy is hopeless at X/Y/Z - I don't know how she copes with life", "Do you remember when Butchy did ...?" Often complete bollox and not remotely what I said to them in the first place.

Have been thinking that going forward I should claim everything is always peachy and I'm the king (queen?) of the world.

No i don't but I know a lot of the opposite which is equally annoying. I'm so poor, I'm so ill all the time, life's so unfair, I'm so unlucky, nothing ever works out for me, my life is so terrible blah blah blah better check my self into a&e on Facebook, pm me hun 🙄

My partner can be like this at times. I just either ignore him or take the piss out of him, he soon shuts up 🤣

why do you care? Seems an odd thing to irritate you?

I love this.
In my experience you don’t have to ask them though.
So they’re just FIGs
Yes people should be able express success, but it’s rare that FIGs observe and positively comment on other's achievements. So it’s a tedious, one-sided, often deluded, boring commentary all the time. Best avoid/change the subject/pretend you’ve missed a call on your phone/leave the room.

Tbf there are a lot of people on MN who’s DC’s are Mensa level intelligent and child model’s. Or who’s DH’s are constantly approached and crushed on by the whole office tinkly laugh

I cannot humour people like this, it shows on my face.🙄
There was a Mum like this on the school run, thought the sun shone out of her daughter's backside. The teacher was apparently wrong about her reading level, always complaining about said teacher, who honestly one one of the most meticulous, and amazing teachers I have ever met. She complained about the child minder being incompetent when she still uses her. Then she loved to rave about all of the sporting activities her daughter does, canoeing, great on school trips, always excelling in everything, understands where all meat comes from because her husband hunts, and they pluck the chicken at home themselves. Great diet, despite her whole family being extremely over weight including daughter, noo medical conditions to cause this; it is her whole household.
She would gloat about neurodiverse children having a lower mental age, and be very condescending with how she had to explain to her daughter that "they" have a lower mental age. The child in question "bullied" her daughter, the poor child isn't a bully, and treats all children the same, with his difficulties. Her daughter couldn't have difficulties like this, it is the parents. She will go on about her job, and how important it is. She then asked another Mum who has MS, if it is the serious kind.
I now actively avoid her.

I have a friend who always talks her husband up, I really like her and she is an amazing, clever, brilliant woman. Her husband is average at best. One day when I get drunk I’m going to ask her why she does it, why she always lists his many achievements and not her own? She is much more impressive than he is, but I think she’s insecure.
I knew another family like this, hugely bigged up the dad and the son’s. The mum was also amazing, full time teacher, mother of five, volunteered on the side, kept an immaculate house but it was all about the dad who was largely absent as he was off getting all these sporting achievements.
All five sons have been persistent cheats and rubbish husbands. They are all divorced. I think they expected their wives to all be equally enthralled with their ambitions and do everything at home whilst they became hero’s of their local community for climbing Kilimanjaro etc. The women all quite rightly said sod that.
Women, don’t boost your man’s ego unnecessarily. Most deserve being brought down a peg or two.

I know someone like this, she is known as The Queen

To be honest, my DH has tendencies to be like this now and again (not all the time.) particularly when it come to his job. 23 people work at his place, and it's open 24/7, every day of the year. (168 hours a week.)

The place runs fine, and functions well, and everyone gets paid on time, all stock is ordered and delivered on time, and the clients seem happy. Yet my DH says - at least 2-3 times a month - that no-one there can do their job properly except him ... Everyone else is useless and lazy and doesn't know what they're doing, even the manager and the supervisor. All useless, can't do their job. He says the place would 'fall apart' without him.

He claims that 3 or 4 staff members there have even told him that they're in awe of how hard he works, how well he does the job, how he always knows exactly what to do, and how 'the place wouldn't run without him.' Like he's some kind of superhero. (I have never heard anyone say this, he tells me they do.) He works 26 hours a week, and isn't there for the other 142 hours of the week that it's open, yet inexplicably, the place runs fine/doesn't fall apart when he's not there! It even runs well when he has a couple of weeks off. It's amazing! 😆

I just say 'yes dear' because I know he's insecure and wishes he had done better in life and had a really highly paid 'top of the pyramid' career. He's done fine though. His job is OK and has reasonable pay, (and he has been employed for 40 years - in 3 different jobs, this one for 13 years.) Also we have our own home, (in a lovely area,) and 2 gorgeous DC, and he has me - the best wife ever, 😆 and we have a couple of nice holidays a year, and friends and close family, and we're both in decent health in our 50s. Seriously, he has a nice life!

Aside from this, I also know/have known people who are very braggy and full of themselves all the time. I HATE people who carp on about how much money they have and what this thing and that thing cost. I don't fucking care mate. Jog on! 😂

I know people like this who tell me how good they are at reading people/ are too nice/kind/generous for their own good. Usually the people who everyone is complaining about or who offer to do lots of wonderful things but actually DO very little. (I liaise with various charities through work so we get A LOT of this!)

My first thought was the latest Markle podcast...it's a masterclass in bigging oneself up.

In real life, I have a friend who has always been like this, if your child has achieved something hers has achieved something bigger and better....now it's her grandchildren who are the best at everything.
Sort of proves people with this trait don't grow out of it...it's for life.

You know what, if you grew up with people doing you down all the time - I did - then it's hard to big yourself up, but it's unhealthy to put yourself down all the time. You have to work on your inner voice first.

I have met people who do this, and I know sometimes it's just big ego, but other times, you know they didn't get anything from their families when they needed it, and they overcompensate. So I try not to judge too harshly.

I know someone who is so extreme with this - we actually find it amusing because it is so awful. When she is asked where she lives she doesn’t say Edinburgh she says oh I live in a penthouse suite in Edinburgh. So cringy!!