The 1841 Census for Fossoway & Tulliebole shows residing at Middle Coldrain :
And'w J Keltie, aged 8
Janet Keltie, aged 14
Christian Keltie, aged 20
Wm G Keltie, aged 25, occupation Ag. Lab.
Isabella Keltie, aged 50
David Keltie, aged 60 (or 61 depending on how you interpret the writing), Farmer
The census entry indicates that Isabella and David Keltie were born in Scotland; but And'w J and the other three were apparently born in England.
I haven't found an entry (yet) for Andrew, but Janet, Christian and William were all born in Rickmansworth, Hertfordshire, England, on 1 April 1807, 30 Jan 1820 and 25 Sep 1814 respectively. There was also an Adam born 5 May 1816 and an Isabella born 7 Dec 1817.
Although one can't say for sure at this stage, you would have to think that Andrew J Keltie was possibly himself born in Rickmansworth, and that David Keltie and Isabella could be his parents.