I don't understand the question, the book says 5+IntMod very clearly in the sidebar. One's bloodline grants them Signature Skills, which are "those skills which can be promoted past Expert proficiency", PF2s equivalent of class skills. No class gets free training in their signature skill.
Huh, that genuinely seems like an oversight. Like there's no good reason that a 10 Int Sorcerer should be trained in 10 skills (1 lore from background) and a 10 Int Fighter, Monk, or Barbarian would be trained in only 4.
Yep 9 + int. Which is odd but the one bonus sorcerers get, otherwise wizards are much better. Of course 4 of them are prescribed by bloodline, but it is four more skills.
Huh, that genuinely seems like an oversight. Like there's no good reason that a 10 Int Sorcerer should be trained in 10 skills (1 lore from background) and a 10 Int Fighter, Monk, or Barbarian would be trained in only 4.