Andrew J. Selsor was born around 1839 in Indiana to Andrew and Nancy Selsor. His father was a farmer who owned $1,500 of real estate and $600 of personal property by 1860. He grew up in Brown, Indiana. By 1864, Selsor was living in Aurora in the Nevada Territory.
He moved to Trenton, Missouri, in the 1860s, and he married a woman named Louisa around 1868. They had at least four children: Ida, born around 1869; Charles, born around 1871; Mark, born around 1874; and Catherine, born around 1880. He worked as a farmer, and by 1870, he owned $4,800 of real estate and $700 of personal property. They moved to Medicine, Missouri, in the 1870s, but they returned to Trenton in the late 1800s. He died sometime after 1900.