the.com/family tree

means A chart that maps how people in a family are related across generations, usually branching out from one ancestor.

from The word grafts a living metaphor onto record-keeping: the tree as a shape for branching relationships goes back to medieval genealogical diagrams, where artists literally drew ancestors along the trunk and branches of a tree (sometimes sprouting from a sleeping patriarch's body, as in the famous 'Tree of Jesse' images in medieval art). The structure stuck because it's intuitive — one root, many limbs, each fork a generation — so 'family tree' became the natural English label once such diagrams spread from church art into everyday genealogy.