It should be a close relationship between flesh and blood
Definition of flesh and blood: refers to parents, brothers, children and other relatives, often (in an extended sense) a metaphor for a closely connected and inseparable relationship.
情: Feelings. Sparse: not close, distant relationship. Estrangement of flesh and blood: refers to the fact that relatives do not interact with each other, and their emotions are also very distant and indifferent.
Antonyms of flesh and blood