Genealogy sites MyHeritage.com and Ancestry.com as well as genealogy programs like RootsMagic, Legacy Family Tree, AncestralQuest, Family Historian, and many others are great for presenting family trees, displaying your data in a straightforward graphical form. However, one Windows program allows you to really understand your tree, to spot problems, links, and patterns you might have missed.
FTAnalyzer is an open source tool for Windows which imports your data in the form of a GEDCOM file, then analyzes it by using a number of useful reports, providing details you might not have uncovered any other way.
To use FTAnalyzer, you have to export your family tree from your present genealogy program or online service as a GECDCOM file. (If you are unfamiliar with GEDCOM files, read my GEDCOM Explained article at http://blog.eogn.com/2014/05/24/gedcom-explained/.) All modern genealogy programs and the leading genealogy web sites all do that although instructions will vary from one such service to another. In most programs and online family tree web sites, you need to find the command to EXPORT your family tree and then follow the menus.
FTAnalyzer produces many reports, including: