Adopted sister. [ He clarifies, in case that brings any sort of understanding to Jim's confusion. ] If we really are from another universe, perhaps things happened differently and Michael ended adopted by a different family. I'm not surprised that he doesn't talk about her, they had a fall out in their youths.

[ Pike doesn't have all the details but even if he did, it's not his place to share. His reason to give James that much information is because the other man really seems to be close to Spock and shocked by the news. ]

So he lives that long. [ His expression changes into a small smile, both sand and relieved. Thanks for letting me know. ] Are you and the younger version very close?