Question: how is bayek related to desmond?
Answer: Instead, it's completely separate from Desmond Miles (AKA Subject 17). Yet, eagle-eyed fans may notice that Bayek shares a resemblance to some of the previous assassins in the series, namely a scar on his lips. Desmond had it, as did Altair (the assassin from the very first game). However, it may just be a coincidence.