Can an illegitimate son be righteous and virtuous, and what advice can be given to a relative suffering from a loss of trust after discovering his truth?

The child of zina (fornication/adultery) bears no sin for what occurred to his mother, and he should be reminded that he is afflicted and must be patient. If his mother was married, he is attributed to her husband, and no attention should be paid to what people say. If she was not married, there is no connection between his being a child of zina and his accountability for his actions. He should fear Allah and not deviate. There is no sin in inquiring about his situation, and we caution that his residing in lands of disbelief (Kufr) could be a reason for his deviation.