So ... someone who is 11 years old and male is not a guy?

"you are having a weird kind of SJW agenda" ... by pointing out that people can become gay versus born gay?

So explaining how things happen is SJW agenda? Maybe you are the one with the SJW agenda, to dis-allow people from explaining how things happen

I am thoroughly confused as to who you are talking about now.

I thought this topic was talking about a child possibly discovering about homosexuality.

Who is whiteknighting who? The boy? The uncle? The mom? Wut?

I neither sided with "keep it a secret" nor "tell the mom to correct him". I cannot disallow anyone from talking about anything.  I am not a moderator. I believe in freedom of speech, which incidentally also applies to me.

Why did I bring up about you being a Social Justice Warrior? Because you think that a 11 year old boy can choose to do anything in their life. No they cannot, because they are a minor and therefore underaged sex is illegal in Malaysia. No idea why you are encouraging something that is both ethically and legally wrong.

I fucking love this.
It's his self-discovery.
And it is totally fine if he is gay.
Also, on your question, whether you should act upon it or even change him

YOU HAVE NO RIGHT TO DO SO.
You have no right to expose him.
You have no right to force his coming out.

He should be doing it on his own and on his own terms.

There is completely nothing wrong with being gay.

He's a kid you dimwit. He could be curious and exploring that doesn't mean he's gay. A dimwit uncle you are.

Though it's still prudent you show the browser history directly to the parents. Don't be sohai and use words like gay. Just show them and let them draw their own conclusion you dimwit.

This isn't about me nor YOU
this is about his privacy and sexuality

You,
don't make it personal

So as per topic, what should i do? He is standard 5 iinm. I dont care if he watches straight porn since i think most of us did the same at that age 

Found out by checking the browser history since he always use the computer in my room whenever im not around to play games and watch youtube. But one particular day he locked the door whereas normally he wont even close the door properly. Since then i always check the history and yeah he did watch it on other days as well.

I want to tell my sister about it so that something can be done to correct him before its too late, but at the same time i dont want my sister and my bro in law to be very disappointed that their son is gay. And also im afraid he will do something with my kids if i expose him, although i can ask my sister to say she found it out herself by checking the browser history

Another possibility would be he was simply curious on how to masturbate 

His google search was always “boy cum” 

So as per topic, what should i do? He is standard 5 iinm. I dont care if he watches straight porn since i think most of us did the same at that age 

Don't allow him access to your PC anymore by putting a password on it. Tell him you know what's he's been surfing and you don't encourage it. Nothing to do with gay porn, at his age he should stay away from any porn. You do not have to inform hi parents but allowing him to continue accessing porn is irresponsible.

As though only can access pc at home.

He may be able to access other PCs but you don't have to make it easy for him. Just because a person is able to buy guns outside doesn't mean you have to give him the key to your gun cabinet.