In which साल Sherlock was born?

The (link) says it was on 6 January 1983 in a reference of the episode The Lying Detective (I don't remember hearing about this info on the episode), but I've heard that there's a book of the series saying it was on 1981 (I never had the book in hands).
So, which one is official?
 In which साल Sherlock was born?
 Helaina posted एक साल  से अधिक पुराना
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