I disagree with the view that "A child adopted under the Hindu Act need not necessarily be a Hindu."
I reiterate section 10 of Hindu Adoption and Maintenance Act, 1956
No person shall be capable of being taken in adoption unless the following conditions are fulfilled, namely :-
(i) he or she is Hindu,
(ii) he or she not already been adopted.
(iii) he or she has not been married, unless there is a custom or usage applicable to the parties which permits persons who are married being taken in adoption.
(iv) he or she has not completed the age of fifteen years, unless there is a custom or usage applicable to the parties which permits persons who have completed the age of fifteen years being take in adoption.
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