Is it ‘my own’ or ‘mine’?

It is important to avoid using or saying my own, his own, our own, their own, her own, your own  when you used them as possessive pronouns.

Instead, it is grammatically correct to use mine, his, ours, theirs, hers, yours as possessive pronouns.

E.g This book is my own mine, their own theirs is to obey.

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However, it is grammatically correct to say or write his own mother, our own teacher, my own book etc. 

In this case, there are identified nouns and own functions as an emphasizing adjective; in the same vein, his, our, and my function as possessive adjectives mother, teacher, book respectively.

In addition to all these, expressions such as this your friend, those our books, that her car can be better written as this friend of yours, those books of ours, that car of hers respectively, especially in standard English.