FreeCEN
http://www.freecen.org.uk/cgi/search.pl lists in 1851 in Rothes George Riach, 33, sawyer; wife Ann, 32 and children Elija, 10; Ann, 4 and Elizabeth, 2; all born Rothes except Ann sr who was born in Duffus.
In 1861 they were still in Rothes: George, 44, railway labourer; Ann, 40; Elizabeth, 11; George, 9; Janet, 5; Simpson, 2.
The children born before 1855 are not in the IGI at
www.familysearch.org but there are four children of George Riach and Ann Hay, two of whom are Janet, born 17 July 1855, and Simpson, born 24 June 1858. So I don't think there's much room for doubt that this is the right family. George Riach and Ann Hay were married in Rothes in 1845.
In 1871 there are George, 53, sawyer; Ann, 49; Elizabeth, 22; Simpson, 12; James, 8; and grandson William Taylor, 4. William will be Elizabeth's illegitimate son, born 28 July 1867 and registered as William Riach as his father is not named.
There's no mention of George sr in
http://libindx.moray.gov.uk/mainmenu.asp but there are several Simpson Riachs mentioned.
I see that a George Sim was born in Aberdour, Aberdeenshire, on the date you state, parents James Sim and Helen Watt. (It might be useful to note that there is also an Aberdour in Fife. The village in the parish of Aberdour in Aberdeenshire is New Aberdour, which is helpful for distinguishing between the two.)
In 1861 the family is living in New Aberdour: Helen Sim, 49, farm servant's wife; son William, 10; son George, 9; and daughter Jane, 21.
In 1851 they were at Lemnas in the same parish: Helen, 40; Elizabeth, 17; Jean, 13, Ann, 8; John, 5; Alexander, 2; William, 7 months.
In 1841 they were at Lemna: Helen, 25; James, 5; Jean, 3; Helen, 10 months.
James sr was evidently working away from home on each census date. He could be the 53-year-old agricultural labourer in the household at Quarryhead in the same parish in 1861; the 43-year-old in Quarryburn in 1851 (I think it's actually the same house because the farmer in both census is a widow named Jane Fowler); and the 30-year-old at Glenhouse in 1841.
As an aside, I see that the Community Contributed IGI says that Elizabeth Riach, daughter of George Riach and Ann
May, was born in Rothes in 'about 1850'. This is a classic example of incorrect information in the 'Contributed' section, and shows why you should never trust any information you find online except images of original documents. In particular, never, ever, believe any online tree. Some are meticulously researched, but others can most politely be described as wishful thinking. Use them to help locate the original documents, by all means.
You need to go to
www.scotlandspeople.org.uk and look up the original certificates and census to verify all this. You should at least go for
- the marriage certificate of George Sim and Elizabeth Riach (to confirm the names of both sets of parents)
- the birth certificate of Janet in 1855 (1855 certificates are a goldmine of information)
- the originals of all the censuses quoted (to make sure that there are no errors in the transcriptions I have quoted).
Once you have done all that, you will have just begun to scratch the surface of the information readily available about your family.