Is it a sin for a newlywed young man to live in his father's house with his mother and 16-year-old brother?

The husband must provide an independent dwelling for his wife where she will not be subjected to harm or embarrassment, as Allah Almighty says: "Lodge them [in a section] of where you dwell, according to your means, and do not harm them to ضيq عليهم (make life difficult for them)." If the wife agrees to live with the family, there is no objection. An independent dwelling means a room for the wife with her private facilities. If the husband is able to provide an independent dwelling but agrees to his wife living with his brother in a house with shared facilities, such that he cannot guarantee against uncovering of 'awrah (private parts) and khalwah (private seclusion with a non-mahram), then he is sinful. However, if he is compelled to live in this house and can guarantee against khalwah, then there is no sin upon him. Sharing facilities with a non-mahram causes great hardship and leads to impermissible acts according to Sharia.