John Brown Niven was born in South Leith near Edinburgh, Midlothian, Scotland on 19 October 1881.
He was the son of John Naismith Niven (1848-1900), a gardener, and Anne Watson Marshall (1850-1899). Both his parents were from Midlothian, his father from Leith and his mother from Edinburgh and they had married around 1868. He had six known siblings: Elizabeth (b. 1869), Robert (b. 1871), Isabella Brown (b. 1873), Thomas (b. 1877), Julia (b. 1880), Elizabeth Anne (b. 1884), David (b. 1886) and James (b. 1888).
The 1891 census of Scotland shows John and his family living at 13 Ferrier Street, Leith, where he was seemingly born and which was described as a green grocer's shop at that time. Both his parents died within a short period of each other and when the 1901 census was conducted John seemingly appeared in England, giving his name as John Naismith Niven, perhaps in honour of his recently-deceased father, and he was listed as a stoker aboard the Pembroke, then docked at Chatham, Kent.
He was married in Southampton in early 1910 to Louisa Lilian Scott 1, née Kindler.
Louisa was born in Southampton in 1865 and was married in her home city in 1889 to Henry Francis Scott, a labourer, (b. 1859 in Horsted, Sussex). The couple would have five known children: Henry Francis (1890-1961), Lily (b. 1893), Harold Louis (1894-1966), Ernest Louis (1897-1972) and Louis Edward (1899-1989). Louisa was a widow by the time she appeared on the 1901 census (her husband having died in late 1899), then living at 130 Priory Road, St Denys, Southampton. When Louisa appeared on the 1911 census, she was still going by the name of Scott and had a further two children, Violet Louisa (b. 1904) and John (1906-2001) and was described as a widow and a general dealer living at 7 Briton Street, St Mary, Southampton. The identity of the father of Louisa's two younger children is uncertain although it is likely that they were fathered by John Niven.
When he signed on to the Titanic, on 6 April 1912, he gave his name as J. McGregor (for reasons unknown) and his address as 7 Briton Street, (Southampton). His previous ship had been the Oceanic and as a fireman he could expect monthly wages of £6. Also aboard was his nephew by marriage Harry Finch.
John Niven died in the sinking. His body, if recovered, was never identified.
His widow Louisa continued to live in Southampton, later at 110 Clarendon Road, Shirley. She died on 24 January 1916.