Hello Liz,

Have you,
looked at every Robert Cain on the 1851 census, single and married, (copy them all down)

...the idea being to check and see all Robert Cain before John Henry 's birth,

then find every Robert Cain on the 1861 Census, single and married, (copy them all down)

then match them with the 1851 Census make note of any Robert Cain that might be missing from the census, (or new ones )

Trace each Robert Cain back to his Parents,

then check both parents Wills to see if John Henry or his Mother Jane are mentioned,

Good Luck !
Averil