This first part of this book seeks to provide increased reliability for the proposition that McManus and O'Conor of the Province of Connaught, Ireland are effectively the same family. This is done through the combined use of historical and genealogical records and the YDNA genetic data from a group of relevant individuals. In the second half of the book a narrative is provided which outlines some of the author's family history research and his return to Kilronan Parish in County Roscommon, Ireland, from where his family emigrated in the mid 1800s and where they had first settled in 1186. A study is made of the complex social system of Kilronan at this time, primarily using the history of its land use and ownership, and the catastrophic events of mid 1800s Ireland - generally referred to as 'The Famine'. To interpret the complexity of the system in which these events occurred, a social systems model is applied. This concludes that the dispersal of the local emigrant population was due to their sensitive dependence on initial conditions in Kilronan and that small non-linear causes disproportionately produced large effects, resulting in their necessary dissipation to other geographical places.