Abstract
The surname Reinach is attached to two families of the early twentieth century. In Germany the phenomenologist Adolf Reinach (1883–1917), and in France the brothers Joseph (1856–1921), Salomon (1858–1932) and Théodore Reinach (1860–1928). This study reconstructs both lines from original civil and community records held in Mainz, Frankfurt, Kassel, Mannheim and Paris. Adolf and the three brothers descend from two sons of Herz Reinach of Mainz (c. 1710–1793/1798): Adolf from Markus (c. 1752–1835), the brothers from Jacob «Jekel» (c. 1748–1820). Adolf was therefore a third cousin once removed of each of the three brothers. A second link runs through the mothers: Adolf's grandmother Fanny Büding and the brothers' mother Julie Büding were first cousins, granddaughters of the Kassel banker Moses Joseph Büding. Through this line Adolf was also a second cousin once removed of the brothers. By Wright's path method the expected shared autosomal DNA is 1.95 per cent, four fifths of it from the Büding ancestors. Five consanguineous marriages in the two families do not alter this value.