John J. McFarland was born on August 11, 1816, in Providence, Rhode Island, to William McFarland and Sarah Moore. His father was a farmer and weaver. The family moved to Washington County, Pennsylvania, before settling in Marshall County, Virginia (present-day West Virginia), in 1834. McFarland married Elizabeth Erskine in 1843, and they had nine children: Eliza, born around 1847; Edgar, born around 1851; Margaret, born around 1854; Robert, born around 1858; and Ralph, born around 1863. He supported the Whig Party until it collapsed in the 1850s, when he became an avid Republican.
The family moved to York, Ohio, in the mid-1840s and then to Linn County, Iowa around 1856. They purchased 160 acres of land, and according to one writer, the “smiling fields soon repaid his efforts, and from time to time he made improvements as his means allowed.” By 1860, they owned $2,600 of real estate and $1,000 of personal property; a decade later, their wealth had grown to $10,000 of real estate and $2,000 of personal property. His wife died on January 25, 1877, and he passed away in May 1900.