Hamilton Atchison was born around 1770 in Ireland to parents Alexander and Mary Hamilton Atchison. He, his parents, and his brother James moved from Ireland to the United States where they first settled in Pennsylvania. In the 1780s, the family moved on to Kentucky. On April 23, 1793 in Fayette County, Kentucky, Hamilton married Isabella Hellena Dennsion. Together they had five children: Alexander, Hamilton, John "Jack," Rebecca, and Malinda. Hamilton passed away at the age 76 in 1846 in Lexington.