Look, I know this may be a controversial pick for some in the Star Trek fandom, but it’s time to accept that Star Trek: Discovery and the rest of the new Trek is just as valid in the canon.
As part of that canon, we now know that Spock was raised alongside an adopted human sister that was taken in by his father Sarek.
Michael Burnham went on to pursue her own career in Starfleet, though in the Prime Timeline, harbored unspoken aggression towards her brother because Sarek reserved an opportunity at the Vulcan Science Academy for him that Michael wanted.