My 11yo brother is causing havoc at home

[Mils011]

My brother has undergone a  complete behavioural change in last 2-4 months in a negative way.
He shouts loudly and rudely whenever we ask him to do anything. He does a lot of drama for a simple thing like brushing in the morning and most of the days, doesn't brush. He gets very angry when we ask him to do everyday chores.
He has been stealing money and buying sweets and keychains etc. He does not share food items, he tries to sneak and eat all tasty food by himself.
Sometimes he would scream and cry when Pappa scolds him. He is not reculent to hit his parents.
Lately, he has started behaving impolitely to other relatives.
Sometimes he is very sweet also.
I had hit puberty when I was 11, so I assumed it was puberty that causes him to behave in such a way.
Is this behavior more than just puberty onset effects?
Does he need treatment? Why can we do?
Thanks for your help!

[specialmom]

A lot of budding teens feel misunderstood.  Listening and attempting to understand him will mean the world to him.  :>)

[specialmom]

So, how old are you?  I would definitely leave this to your parents.  Absolutely puberty can start at 11 and kids can get moody and difficult.  They fight being told what to do.  I have  13 and 14 year old boys.  I experience it daily.  :>)  The other possibility is that something is happening to him.  If he is, for example, being bullied or has found drinking or drugs, etc.  A behavior change can result.  But otherwise, this is puberty angst and pretty normal.  Boys get grumpy and start also spending time away.  Even if in the same room, they are 'away' (headphones while on ipad).  I never thought it would happen to my younger, good natured and sweet child.  Nope, the teenage bug hit him too.  It's also an important time to let them make some decisions for themselves.  If it is hair brushing and they don't want to do it, let them suffer the consequences of bed head in public.  If it is teeth brushing, tell him the expectation and remind him that he has to go to the dentist and that lack of brushing WILL have consequences.  good luck

[Mils011]

Hello! Thanks! I'm 18. I'm basically here on behalf of my mom.
Today, he's a nice sweet boy.
I hope it's just him being 'teenagery'.
Luckily I can handle him to an extent by treating him how I wanted/want to be treated in a specific situation.