in the blood
Innate, as of a skill or quality. That type of passion can't be taught—it's in the blood.
in the blood
and in one's bloodFig. built into one's personality or character. John's a great runner. It's in his blood. The whole family is very athletic. It's in the blood.
in the/somebody’s ˈblood/ˈgenes
part of somebody’s nature and shared by other members of their family: Both his father and his mother were writers, so literature runs in his blood.