Cojeen, Cogeen, Codgeen, Cotteen, etc, all phonetic variations of the same name.
No standard names at this time, the clerk wrote as he heard and as much of the population was illiterate they had no means of checking.

Censuses - The Isle of Man and UK census are taken in the '1' years, US in the '0' years.

Earliest useful one for the IoM is 1841 but no family relationships were recorded and ages over 14 were usually (not always) rounded down to the nearest 5. John appears to be not rounded, but the other could be.

1851, Lonan, district 4, schedule 14, Barroose
William Cowin, head, married, 67, weaver, Lonan
Isabella, wife, married, 62, Lonan
John, son, unmarried, 24, mine labourer, Lonan