Re: STID and the Eugenics Wars books
^The question isn't about what the basis for Marla's deduction was, the question is whether the episode itself established Khan as a Sikh in dialogue. And it did so in two ways: one, by having Marla state it outright, and two, by giving him the surname Singh.
But do only Sikh men have the last name of Singh?
I know we had a Lieutenant Singh in Lonely Among Us
"If I hadn't tried, the cost would have been my soul." - Admiral James T. Kirk, Star Trek III: The Search for Spock