OK using the fact that John had a much older sister named Elizabeth, I believe this may be the family on the 1851 & 1841 UK Censuses BUT would appear that Catherine (mother) may have emigrated to the US after the death of her husband and that John may have been born to an widowed "unwed" mother......
RULE Catherine Head W F 39 Miners Wife Pauper Cornwall - Stoke Climsland RULE Elizabeth Dau - F 11 Scholar Cornwall - Callington RULE George Son - M 9 Scholar Cornwall - Stoke Climsland RULE Fanny Dau - F 7 Scholar Cornwall - Stoke Climsland RULE Joseph Lodger S M 27 Miner Cornwall - Camborne RULE Jane Visitr - F 11 Miners Daughter Cornwall - Camborne
JONAS Henry M 58 Ag. Lab. Cornwall COLLINS Elizabeth F 33 Cornwall COLLINS Elizabeth F 3 Cornwall COLLINS Jane F 1w Cornwall RULE James M 25 Miner (Copper) Cornwall RULE Catherine F 23 Cornwall RULE Elizabeth F 2 Cornwall HELSON George M 2 Cornwall
And this is most likely the marriage =
Marriages March Quarter 1838 JonasCatherineLauncestonVolume 9Page 175 RULEJamesLauncestonVolume 9Page 175
Deaths March Quarter 1848 RuleJamesLauncestonVolume 9Page 109