St. Mary's County colonial records were lost in a courthouse fire, but we know from early national records that the family was free during the colonial perod. They were probably related to the slaves listed in this inventory which was recorded in the Prerogative Inventories and Accounts, 1714-1717, volume 36C, p.219 (which were kept in Annapolis):
Inventory of John Manning of St. Mary's County, deceased
1716,
1 negro man called Adam - 14 pounds
...
1 malato man called Tho: Adam - 30 pounds
1 malato man called John Adam - 30 pounds
1 malato man called John - 30 pounds
Paul