he was born isaak seligmann in baiersdorf, erlangen-hochstadt, bayern, germany (bavaria), to david isaak seligman and fanny steinhardt. he was the youngest of eight brothers, all of whom emigrated to america and became involved in running various branch offices of the merchant banking house j. & w. seligman & co., co-founded in manhattan, new york city in 1846 by isaak's elder brothers, james and joseph seligman. isaak later changed his name to isaac, and in august 1857, at the age of 23, seligman joined his entrepreneurial brothers in the united states.