WP Family Tree is a family tree generator plugin for WordPress, by Arvind Shah and Sunil Shah. Each family member have their own post within a “Family” category. In the family member posts you can specify birth dates, mother, father, etc. A complete family tree can be displayed on any page with the [family-tree] shortcode.
The root of the tree can be specified with the root parameter: [family-tree root=’John Doe’]
Plugin homepage: http://www.esscotti.com/wp-family-tree-plugin/