How can you find names of parents of kids born in early 1800's when the only census you find has the surnames

the childrens name were lucinda Clements born 1816, George Washington Clements born 1822, Robert Clements born 1829, Mary Ann Clements born 1834. I've found in doents that all the children were born in Kentucky except for George Washington Clements , he was born in Tennessee. Also, I've seen seen on census where Lucinda stated her father was from Virginia, and mother was from Kentucky.