John Borthwick Crosbie was born in Croydon, Surrey, England in 1867 and his birth was registered in the first quarter of that year. He was the son of a Scottish father, Adam Borthwick Crosbie (b. 1840 in Edinburgh) and an English mother, Margaret Bockless (b. 1845 in Woolwich, Kent). John had two siblings, Grace (b. 1866) and Helen Luke (b. 1870).
John first appears on the 1871 Scotland census living at 362 Castle Hill, Edinburgh, Midlothian, and his father was described as a brass finisher. His mother died in 1872 and his father was remarried in 1879 to Midlothian native Jane Murdoch (b. 1855). Together they would have three more children: Robert (b. 1881), Adam (b. 1884) and Marion (b. 1887). On the 1881 census John is listed with his family, including new stepmother, at an address in Newington, Edinburgh. He was at this time aged 14 and described as a plumber's apprentice. John is absent from the 1891 census, but his family are now living at 11 East Richmond Street, Edinburgh.
John was married in Hastings, Sussex in late 1896 to Elizabeth Mary Jane Bridger (b. 1867 in Wick, Sussex) and they had two daughters: Marie Frances Mary Crosbie (b. 1897) and Elizabeth Catherine (b. 1900). The family appear on the 1901 census living at 68 Cambridge Road, All Saints, Hastings. John at this time was described as a Turkish Bath Steward. The family appear to have moved north for a while as his daughter Elizabeth died in Chorlton, Lancashire in 1904. On the 1911 census John and his family are now living at 47 St Dunstans Road, Hammersmith, London. At this time he described himself as a masseur and chiropodist but it is not stated whether he worked at sea at this point.
When he signed-on to the Titanic 1, on 9 April 1912, he gave his address as 47 St Dunstans Road, (Hammersmith). His last ship had been the Olympic. As a Turkish Bath steward he received monthly wages of £6 10s 2.
Crosbie died in the sinking. His body, if recovered, was never identified.
John's widow did not remarry and she died in London in 1931. His daughter Marie never married and died in Uxbridge, Middlesex in 1952.