According to his birth record, Rudolf Daniel Purath was born on July 2, 1874 in the village of Marianki in the Sierpc Evangelical parish, Russian Poland (present-day Republic of Poland). He was baptized on July 3, 1874. His parents were Stephan Purath and Elisabeth Kratzke - they were part of the extensive German diaspora living in Poland. Rudolf had an older sister Emilie Purat born in 1871, and a younger brother Gustav Porat born in 1877, as well younger half-siblings Bertha Otillie Tober in 1879, and Christian Friedrich Tober in 1883, as his mother remarried after the death of his father in 1877. Sadly, Rudolf's mother also died in 1886, when Rudolf was only 11 years old.

Rudolf immigrated to the US in 1896, arriving in New York City on April 11 aboard the SS Phoenicia from Hamburg, Germany. In the United States, Rudolf spelled his surname as "Porat" - it is believed that this alternate spelling originated with the pastor of the Sierpc Evangelical parish, who transliterated the Purath surname into Russian (which uses the Cyrillic alphabet) as "Porat". When transliterated back to the Latin alphabet (English), this spelling was maintained. For some reason, Rudolf rendered his birth date in the US as either June 11, 1875 (his marriage record and WW1 draft registration card), or June 17, 1875 (his Naturalization paperwork and Social Security application. It is not known why these dates differ from his birth record? Is it possible that his birth was recorded incorrectly by the Pastor (only the month and day; there is no way the year could be wrong - he was definitely born in 1874).

Rudolf married Emilie (Amelia) Reinholtz on August 3, 1902 in Brooklyn. They had 3 children:

Gustave Henry - born 1903
Olga Amelia - born 1909
Freda Elizabeth - born 1917

Rudolf died in 1964 at the age of 90. His wife Amelia preceded him in death 2 years earlier.