There are 62 Carey's in the Griffith Valuation of Kildare
in 1853, census substitute. There are 0 Carey's in Kilcock at that time.
Kilcock is a Parish, a Townland and a Town in Kildare
in the Union of Celbridge (within 12 mi.)
You could try the Tithe Applotments as tax and it is used as a Census Substitute, these range in dates from 1820-1839 depending on the county. That would put the date back to his father's time hopefully.
There is a military message board called MILGENIRE that might be worth a google.
Kildare belongs to a not for profit Historical Foundation with birth and marriage records, although not for profit fees are charged.
Parish Kilcock & Newtown baptisms from 1771-1899 and
marriages same but with a gap 1788 to 1834. You should have no trouble finding a birth record. A birth record should have the father and mother's name and her maiden name.
Once you have the mother's name you can try for the siblings.