Just as a physical house relies on its invisible foundation to stand, a child's success (the 'house') relies on the sacrifices, character, and spiritual inheritance (the 'blood') of their ancestors. It teaches that individual achievement is never truly solo; it is a manifestation of ancestral effort. Neglecting these roots ensures the eventual collapse of the 'son's' structure.
The blood of the father is the foundation of the son's house. Respect your origins to secure your future. Your current height is built upon the sacrifices of those who came before you.