All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is the responsibility of elders to provide the good and religious environment for their youngsters from the beginning. They have to watch their friends and their activities.
Parents are not allowed to disown him or kill him rather they should exhort him and remind him of the bad consequences of such an act in both lives, asking Allaah to grant him steadfastness and righteousness. We mentioned the ruling of killing a Muslim in a similar case in our Fatwa: 86080.
"As for killing her, this is not allowed, because, if she does not regard her act as lawful, she is still a Muslim." The same Fatwa further reads, "As regards disowning her, if what is meant by that is to remove her from one's lineage, that is impossible and unlawful in Islam. But if what is meant by that is to disinherit her, her parents cannot do that if she does not regard her acts as lawful."
It is strongly advised to keep him away from such an environment by any means. If this can only be achieved by sending him to a country or place where he can control himself and cannot practice such a sin, it must be done. However, it is mandatory to exert all the possible efforts and use all means to prevent him from this sin. If all the efforts do not succeed then he should be kept away from his siblings to avoid having a bad influence on them.
Marriage can protect him from this sin and thus his parents, or the responsible persons should get him married him as soon as possible if he is able to carry out his marital responsibilities.
However, living in a non-Muslim country is not allowed as we mentioned in Fataawa: 81464 and 81642.
Allaah knows best.