A family tree, or pedigree chart, is a chart representing family relationships in a conventional tree structure. The more detailed family trees used in medicine, genealogy, and social work are known as genograms.
Genealogical data can be represented in several formats, for example as a pedigree or ancestor chart. Family trees are often presented with the oldest generations at the top and the newer generations at the bottom.
An ancestry chart, is a tree showing the ancestors of an individual, will more closely resemble a tree in shape, being wider at the top than the bottom. In some ancestry charts, an individual appears on the left and his or her ancestors appear to the right.
A descendancy chart, which depicts all the descendants of an individual, will be narrowest at the top.
Family trees can have many themes. One might encompass all direct descendants of a single figure, or all known ancestors of a living person. Another might include all members of a particular surname (e.g. male-line descendants). Yet another approach is to construct a tree including all holders of a certain office, such as kings of Germany. This relies on dynastic marriage to hold together the links between dynasties.
One technique is a fan chart, which features a half circle chart with concentric rings: the person of interest is the inner circle, the second circle is divided in two (each side is one parent), the third circle is divided in four, and so forth.
For instance, the longest family tree in the world today is that of the Chinese philosopher and educator Confucius (551 BC-479 BC), and he is the descendant of King Tang (1675 BC-1646 BC).
The tree spans more than 80 generations, and includes more than 2 million members. An international effort involving more than 450 branches around the world was started in 1998 to retrace and revise this family tree. A new edition of the Confucius genealogy was printed in September 2009 by the Confucius Genealogy Compilation Committee, to coincide with the 2560th anniversary of the birth of the Chinese thinker. This latest edition is expected to include some 1.3 million living members who are scattered around the world today.
Another very old and extensive tree is that of the Lurie lineage which includes Sigmund Freud, Martin Buber, Rashi, Hezekiah and traces at least back to King David born (1037 BC).