As you can see from Jean Bain's age, they started work early in that era.
No Guarantees, oof course, that this is the correct JF.
It looks as though you have found JF's Birth on either SP or on the secondary source, the LDS Family Search site-
John Forbes Scotland, Births and Baptisms, 1564-1950
07 Feb 1826
parentJohn Forbes, Ann Thaw
You should be able to VIEW and Download a Scanned IMAGE of the original document on SP.
Depending upon how the local incumbent maintained the (old) Parish Register, there might be entries on the same page giving further information about JF Jr.
Some OPRs had separate ledgers for Birth, Marriages, Deaths and other aspects of parish life.
Some kept them all in the one book, serially as they occurred. One of this format had some interesting revelations regarding reprehensible behaviour.
As you can access FMP, you should have no technical problems getting on to SP - the holding company are one and the same, Brightsolid, owned in turn by D C Thomson of Dundee, publishers of the Dandy and the Beano.
As the majority of those records have been scanned and are available immediately and cheaply on-line, it is highly advantageous to access them.
1841 census transcription details for:Wester Kincardine, Wester Kincardine, Kincardine (Inverness) Print Close National Archive Reference: RG number: Piece: 209 Book/Folio: 6 Page: 3 Reg. District: Sub District: Parish: Kincardine (Inverness) Enum. District: Ecclesiastical District: City/Municipal Borough: Address: Wester Kincardine, Wester Kincardine, Kincardine (Inverness) County: Aberdeenshire Name Relation Sex Age Birth Year OccupationWhere Born ANDERSON, JohnM 26 1815 Farmer Aberdeenshire ANDERSON, AnnF 45 1796Aberdeenshire THOMSON, AnnF 20 1821 F S Aberdeenshire ANDERSON, AndwM 20 1821 Ag Lab Aberdeenshire FORBES, JohnM 15 1826 Ag Lab Aberdeenshire SMITH, JohnM 12 1829 Ag S Scotland