When it was revealed that Michael Burnham would be Spock’s adopted sister, fans wanted to know about her relationship to Spock and why she was never mentioned by Spock.
Executive Producer Alex Kurtzman is aware of the questioning and addressed the issue in a recent interview with Digital Spy.
Making Burnham a relative of Spock “evolved from the storytelling,” said Kurtzman. “The first Vulcan you’re going to think of when you think of Vulcans is Spock, so as the story evolved, it became an interesting exploration of, ‘Wait, how could they have been potentially living in the same home, under Amanda and Sarek, and Spock has never mentioned her?'”
“When we got into that dramatic questioning, it became a fascinating idea and we locked in on it,” Kurtzman added. “It was never about playing it safe. In fact, I would probably argue with some people that that’s not a choice that plays it safe.
“However, a lot of people are going to have a real issue with it and now it’s incumbent on us to prove why that was the right choice.”
This isn’t the first time that Spock acquired a new relative. “Well, it certainly means there’s precedent for it,” said Kurtzman. “Listen, Vulcans are very tight-lipped. They don’t go around talking about their emotional experiences unless it’s necessary, so that helped us in making the decision.”
Source: Digital Spy