An Ahnentafel is a genealogical numbering system that allows one to list a person's ancestors in a particular order. It is also known as the Sosa-Stradonitz Method, for Jérôme de Sosa, the Spanish genealogist who popularized the numbering system in 1676 and Stephan Kekulé von Stradonitz, the German genealogist who published his interpretation of Sosa's method in 1898.

In an Ahnentafel each person's father is numbered twice that of the person. Each person's mother is two times that person's number plus one.

Set Your Family Tree Root

Log on to your online family tree as "Wizard", then select an individual and click "Update - Individual/Family". This will open a window that shows you a list of available update options. Click "Set to home individual" to set the selected individual as your family tree root.

Sosa numbers will be automatically assigned to your family tree root ancestors.

Clicking the Sosa number of any person will open a window that shows you a descendancy list.

Remove Your Family Tree Root

If needed, you can deactivate the numbering system. Select the "Online Family Tree - Manage - Expert Options" menu item then click "Remove the family tree root". Note that this will not remove the individual in your family tree!