Idiom
in the blood and in one's blood
Theme: AFFINITY
built into one's personality or character.Johns a great runner. It's in his blood.The whole family is very athletic. It's in the blood.
Slang
in one's blood
Theme: GENETIC
mod. inborn; part of one's genetic makeup.It's in my blood. I can't help it.Running is in his blood. He loves it.