According to Official Guinness Records,
The largest family reunion is 4,514 and was achieved by the Porteau-Boileve family at Saint-Paul-Mont-Pénit, Vendée, France, on 12 August 2012.
The family tree traced by Jean-Michel Cheneau, direct descendant of Georges Porteau and Madeleine Boileve, shows that the family were founded by this couple in the 17th century.
For a complete list of 2012 records, please visit 2012 Guinness Records in France.