A family tree is a chart representing family relationships in a conventional tree structure form resembling a tree. As normally presented these trees "grow" down from the top, from the oldest generations at the top to the newer generations at the bottom. Family trees are an essential tool in genealogy. A tree showing the descendants of an individual (illustration right) will more closely resemble a tree in shape; one showing the ancestors of a individual (illustration below in "The Family Tree of Sigmund") will be wider at the top than the bottom. The convention is usually to show successive generations moving down the chart.
The image of the tree probably originated with one in medieval art of the Tree of Jesse, used to illustrate the Genealogy of Christ in terms of a prophecy of Isaiah (Isaiah, 11, 1). Possibly the first non-Biblical use, and the first to show full family relationships rather than a purely patrilineal scheme, was several family trees of the classical gods in Boccaccio's Genealogia deorum gentilium (On the Genealogy of the Gods of the Gentiles), whose first version dates to 1360. From the earliest manuscript copies the trees are included, and they were probably part of the original work.
|Mom||Dad||Uncle Jake||Aunt Lisa|