Is it permissible for an adult adopted son (20 years old) to continue sitting with his adoptive mother (55 years old) who did not breastfeed him?

A woman's adoption of a child does not confer the legal status of sonship, and it is not permissible to treat him as a son regarding physical contact, seclusion, or inheritance. Rather, it falls under the category of sponsorship (kafalah), which carries great reward.

If the child reaches puberty, he is not obligated to leave the house, but he is considered a stranger to her if there is no reason for mahramiyyah, such as suckling.

If there is no mahramiyyah, she must observe complete hijab in his presence, and it is not permissible for her to seclude herself with him without a mahram.