I've only just seen this post which is very interesting.
I descend from John Killey (b. Santon 1810). I did a lot of research back in 2005 and I came to the conclusion that his parents were John Killey and Mary Callow. Frustratingly, I could never find definitive proof. But all the information on these recent posts seems to back up the theory that all these siblings - John, William, Phillip, etc were the family of John Killey and Mary Callow. It would be great if someone, somewhere could find the proof.
My John Killey married Jane Hutchin in1832 in Jurby and had 6 children as listed in one of the earlier posts - Catherine (b. 1833), John (1834), William (1836), Jane (1840), Anne (1844) and Thomas (1848), all born in Jurby. I too got that information from the IGI.
John Killey (1810) worked as a lead miner in Laxey and died there on 4 December 1882. His wife Jane Hutchin died on 4 April 1901 in Lezayre at the ripe old age of 87. She died just days after the 1901 census was taken, so I managed to find her in all 7 censuses from 1841 to 1901! There can't be many people with that distinction!
My direct ancestor is Jane (1840). She married an Irishman, Patrick Rodgers, in Kirk Maughold in 1865 and they left soon after to live in Cleator Moor, Cumberland. It's interesting that once in Cumberland she stated her maiden name as Gill - echoing what one of the previous posters said.
I'm sorry I can't add anything on who the parents of John Killey and Mary Callow were but hopefully you will find this Killey information interesting nonetheless.
If anyone does come up with other lines of enquiry I'd be as curious as Jane Elder to find out too.