Asalam Walikum, how do would you handle a situation if your child is part of the LGBTQ+ community? Since Islam prohibits it, I don't want to disown a child so what would be the right way to handle it?
Below is a preliminary answer to your question. I may change it if I find out more. I probably know more than most Muslims about homosexuality due to my wide reading of Western sources, but I do not claim to be an expert.
Having homosexual inclinations in itself is not a sin. It is only sinful if it is acted upon. Therefore if one’s child comes forward and claims they are gay, they should be told that both natural (genetic) and environmental factors contribute to whether a person feels attracted more to their own sex or the opposite sex. Sexual attraction is on a spectrum–most humans are capable of being attracted to their own sex given the right circumstances (note the extremely high rates of reported homosexual activity among prison inmates and monks).
Among monozygotic twins, if one of them identifies as homosexual, there is a 24% chance that the other twin will also self-identify as homosexual according to a large study of 4901 twins (there are studies that report higher rates). This suggests that about 24% of sexual preference may be genetically-mediated and and 76% of it environmentally-and-psychologically-mediated. While we should not dismiss the existence of built-in factors (genetic, epigenetic) that promote homosexuality, the fact that monozygotic twins only have a 24% chance of both identifying as gay shows that there is a lot of fluidity in sexual preference, meaning that most people with homosexual genes are likely to be able to enjoy relationships with people of the opposite sex.
There is a small minority of homosexuals who find the very idea of touching a person of the opposite sex repulsive. Such people often have a history of sexual abuse if the reports I have seen are representative. This minority likely does not represent the majority of people with genes that promote homosexuality. The majority are likely to be able to enjoy relationships with both sexes.
So a Muslim child who “comes out” as gay should be told that they will likely be able to enjoy life with the right person of the opposite sex. But if they are completely opposed to that idea, they should be told that their only other option is celibacy. There is nothing wrong with homosexual desires in themselves as long as they do not act on them.
Many people are born with far worse conditions than not feeling attracted to the opposite sex–such as being born blind. There are also millions of heterosexual Muslims who desire marriage but cannot marry due to not having enough money or not having suitors. A Muslim who believes they are homosexual is just another Muslim who is unable to marry. If they want to please God, they would either choose celibacy or wait until they find the right person of the opposite sex.
For a discussion of why Islam forbids homosexual relationships please see this essay.
If the child wishes to live a homosexual lifestyle
Now, if one’s child wishes to break Islamic law and engage in homosexual relationships, their treatment is similar to a heterosexual child who engages in sexual activity outside of marriage. According to a fatwa by the Qatari Fatwa Authority, it is permitted to maintain familial contacts with such a person. The recommendation is actually to maintain contact (while advising them to stop what they are doing). According to Dr. Suʿād Ṣāliḥ of Al-Azhar University the treatment of such a person is similar to the treatment of a family member who has become a disbeliever. The Quran says regarding treating parents who are disbelievers:
We have advised the human being to be good to his parents. But if they urge you to associate with Me something you have no knowledge of, do not obey them. To Me is your return; and I will inform you of what you used to do. (The Quran, verse 29:8)
The Quran does not recommend any action against them other than not obeying them. Many other scholars from Al-Azhar University also expressed the opinion that sinful family members should not be shunned but treated with kindness, knowing that God is forgiving and that they may one day change.
So Islam does not recommend disowning such a child. They should instead be treated with love and respect while it should be made clear to them that their behavior is unacceptable. But harassment of them is not a good idea either and may only lead to their feeling oppressed and misunderstood. So if they mention that they think they are gay, they should be told that their only options are either celibacy or finding a person of the opposite sex that they find attractive. After this the issue should be left alone. If the child does not bring it up again, the parents should not bring it up either. Perhaps the child will change his/her mind in five or ten years. It is not the job of the parents to force the child to stop desiring their own sex, and once they get older they are free what life they lead.
The Qatari Fatwa Authority also says that it is obligatory for parents to give a living allowance to a child who has renounced Islam. Parents are also entitled to a son’s wealth if they are poor even if they are disbelievers. The same would apply to a child who lives a homosexual lifestyle; their homosexual lifestyle does not cause them to lose their rights to the help and support of their families.
According to a Saudi fatwa, fathers are obligated to give a living allowance to their unmarried daughters even if they live a sinful lifestyle.