I looked for all of them in Ancestry and FamilySearch but didn't find any Census or Vital Records. I did find two other family trees and Jess became a reknown preacher who moved around Texas establishing churches and then moving on. Neither of these family trees had anything other than 1860 Robertson County Census for Jinsy.
Most larger public libraries provide free access to Ancestry.com if you have a local library card.
One tree said that Jess died 16 Aug 1920 in Jefferson Co. TX. There is an obituary volunteer for that county at www.gengathering.com
. You do have to create a user ID and password to enter that web site but access to the volunteer info is free. Hopefully threre will be some mention of his mother.
I also found a J B Downing on the Tax Assessment records 1889-1891 in Bell Co. but there wasn't any additional info. Just the name and livestock and property owned. I don't think J. B. was Jincy. Successful Searching!