bound by blood, not bloodlines

from Web MD:

"The original meaning of the saying “blood is thicker than water” is that family ties are the tightest of all.

  • YOUR ANSWER: True

  • CORRECT ANSWER: False

Actually, it’s quite the opposite. In Middle Eastern culture, blood brothers -- warriors who share blood they shed in battle -- are even closer than biological brothers. An earlier expression is that blood is “far stronger than the water of the womb.” Historians think wealthy Englishmen may have bent the meaning to stress the importance of bloodlines and keep money in the family."