Fanny Alger was born to Samuel Alger and Clarissa Hancock Alger on September 20, 1816, in Rehoboth, Bristol, Massachusetts, just east of Providence, Rhode Island. Samuel, a thirty-year-old Massachusetts carpenter, had built a home for Heber C. Kimball’s father in New York in 1810. Clarissa, twenty-six, also from Massachusetts, was a sister of Levi Hancock, who would become a stalwart Mormon, be ordained one of the presidents of the seventy in 1835, and serve as the chaplain of the Mormon Battalion. Fanny was the fourth of eleven siblings. The Algers’ first five children, all born in Rehoboth, were: Eli Ward (1809), Samuel (1811), Saphony (1813), Fanny herself (1816), and Amy Saphony (1818). Samuel and Saphony died young.

The Algers moved to Lebanon Township, Ashtabula, Ohio, in the northeastern corner of the state, where John, Alva, and Samuel H. were born in 1820, 1822, and 1826. They then drifted west to the Cleveland and Kirtland area, where Thomas and Clarissa were born in Mayfield, Cuyahoga County, ten miles southwest of Kirtland, in 1828 and 1830.

That same year, in November, when Fanny was nearly fourteen, her father converted to Mormonism in Mayfield. Clarissa was evidently baptized about the same time by Parley Pratt. It is not known when other family members were converted, except for John, Fanny’s younger brother, who was baptized by her maternal uncle, Solomon Hancock, in Mayfield in March 1832.