Homosexuality, whether it is among men or women, is one of the most abhorrent of immoral and evil actions that a person may commit, and is one of the most shameful deeds in this world and in the hereafter. Ibn al-Qayyim (may Allah have mercy on him) said concerning the one who commits this act that he has committed so great an evil that there is no hope that he will ever be reformed after that; it takes away all his good deeds and removes all modesty and shyness, because after that he will not feel shy before Allah or before His creation.
Indeed, Allah, may He be exalted, destroyed an entire town along with its people, namely the town of the people of Loot, because of this immoral action. See the answers to questions no. 10050, 38662 and 20068.
What you must do for your brother is tell him of the shame in this world and in the Hereafter that results from this evil, that it will ruin his spiritual and worldly interests, and that he will become insignificant to Allah and to other people if he persists in it. Warn him of the consequences and the shari ruling on the one who does that.
Then you have to block every means that makes it easy for him to do this immoral action or that calls him to it. If you can move him from the place where he is studying, where he began to find out about these homosexual websites, then you should do so. If he is under your guardianship and you are responsible for him, then you should prevent him from doing that by all possible means. You should remember that you are responsible for him so long as he is under your care and authority.
In fact, even if this sinner was not your brother or you did not have any authority over him, your duty would still be to strive by all possible means to remove this evil that you see and prevent him from doing it, and to advise him for the sake of Allah and warn him of Allah's punishment.
Muslim narrated in his Saheeh (70) that Abu Saeed al-Khudri (may Allah be pleased with him) said: I heard the Messenger of Allah (blessings and peace of Allah be upon him) say: Whoever among you sees an evil action, then let him change it with his hand [by taking action]; if he cannot, then with his tongue [by speaking out]; and if he cannot, then with his heart - and that is the weakest of faith.
These signs that you see in your brother's appearance, namely his clothes and outward appearance, and the way he speaks, are all evil actions that lead to homosexuality and immorality, even if you do not know that your brother has committed that action. So how about if he were to exhibit signs indicating that he has committed that action?
It was narrated that Ibn Abbaas (may Allah be pleased with him) said: The Prophet (blessings and peace of Allah be upon him) cursed effeminate men and masculinised women and said: Expel them from your houses.
Narrated by al-Bukhaari, 5436
Al-Mubaarakfoori (may Allah have mercy on him) said:
That is, men who imitate women in appearance, clothing, using henna, voice, speech and all their movements. Such actions are prohibited because it comes under the heading of changing the creation of Allah.
Effeminate men are of two types. One type is those who were created like that and are not trying to imitate the attitude of women and the way they dress, speak and move. For such people, there is no blame, sin, shame or punishment for them because they are excused.
The second type is those who deliberately imitate women in their attitude and movements, and imitate the way they speak and dress. These are the ones who the hadeeth says are cursed. End quote.
We ask Allah to make things easy for you and to set your brother's affairs straight and help you to discipline him.
And Allah knows best.
Reproduced from Islam QA