Seth Probasco's parents were George W. Probasco b. 1803 d. 1884 and Lucretia Trowbridge b. 1817 d. 1894. In the 1850 Federal Census he was living, along with John Parr, Minor Trowbridge who was his grandfather. Seth was one of 5 children of George and Lucretia: Catherine (d. young), Seth T., Myron H., Creighton L. and Deborah.