Cynthia Alexander Stevenson was the second of twelve known children of Robert Montgomery Young Stevenson Sr. (1772-1835) and Maria Rebecca (went by Rebecca) Steele Stevenson (1775-1839), who married c1795 in North Carolina. Cynthia was born near Statesville, Iredell County, North Carolina. Her grandfather William "Little Gabriel" Stevenson (1725-1809) had donated land to found the city.

The Robert Stevenson family was known to live in Lincoln County, North Carolina in 1797 and they are thought to have moved west in about 1806 and settled first in Christian County, Kentucky, where a number of relatives lived. From there Robert took a trip to Missouri and then took his family there, arriving on 30 Nov 1807 at Caledonia, present-day Washington County, Missouri. Robert was active in the Presbyterian Church, was a farmer, teacher, and a member of the Missouri state legislature. He moved to present day Butler County in 1830 where he and his wife died.

Cynthia married Timothy Phelps (1788-1863) on 25 Mar 1825, near Belgrade, Washington County, Missouri. Timothy was a veteran of the War of 1812. Cynthia and Timothy lived their entire lives in Washington County, Missouri and were the parents of eight known children:

1. Robert Montgomery Phelps (1828-1912)
2. Henry A. Phelps (1829-1899)
3. Elizabeth Greene Phelps Breckenridge (1830-1907)
4. William Sloan Phelps (1832-1905)
5. Rebecca Jane Phelps (1833-1913)
6. Samuel Phelps (1834-1880)
7. Amanda Maria Phelps Bryan (1838-1918)
8. Lysander Flinn Phelps (1839-1863) (FAG memorial 3166930)

Links to Cynthia's parents, husband and six of her eight children are included below. The son Samuel Phelps died at Joplin, Jasper County, Missouri but it is not known where he is buried. The son Lysander died of pneumonia while serving with the 33rd Regiment, Missouri Infantry, Union Troops during the Civil War at Helena, Phillips County, Arkansas.