King Daniel Into Darkness wrote:
That he was a Sikh or from Northern India primarily.
He might still be, what with the theory I've heard that Marcus had Khan surgically altered, to make doubly certain no one would recognize him.
Two things to consider: One, Sikhism is a religion rather than an ethnicity; and two, there were British people living in India for centuries and there are still hundreds of thousands of people born and raised on the subcontinent who are of British ancestry. So looking like Benedict Cumberbatch is not necessarily inconsistent with being a Sikh from Northern India.
After all, Naveen Andrews, who's been cited as a more credible possibility for Khan because of his Indian appearance, was born in London, England to Christian parents. So why couldn't the reverse happen as well?