John Colthart was born on April 25, 1833 in Crawfordjohn, Lanark County Scotland. He was the only son of James Colthart (1788-1862), a master shoemaker from Crawfordjohn and Janet Somerville (1796-1833). His mother died when he was 6 months old and he was rasied by his father's brother Thomas Colthart (1784) and his wife Alison Watson. Thomas and Alison had eight children of their own.

At age 22 John emigrated to Tasmania, Australia arriving in Hobart in the vessel "John Bell" on December 4, 1855. In the ship registry he was listed as a shepard. From Hobart he traveled on to Launceston in the vessel named the "Duncan Hoyle". He married Ann McMillan on December 31, 1857 in the Presbyterian Church in Launceston. John and Ann had two children: James Samuel (1860) and a baby (1862) that died at birth. Ann also died during the birth of their second child on March 15, 1862. Shortly after Ann's death, John left Australia for New Zealand and did not return. His two year old son James was left behind in Tasmania to be raised by another family.

John married his second wife Elizabeth in New Zealand in 1876 and they had two daughters. He died there in 1937 at the age of 104.

• James Samuel Coltheart (1860-?) was born on February 13, 1860 in Tasmania. Following his mother's death, when James was age 2, he was raised by another family and bore the surname Williams. He grew up in Launceston and on maturity became a carpenter/builder. James was apparently advised of his real name when he was to be married in 1884 and no one was quite sure how to spell the Colthart name. The surname was spelled incorrectly on the marriage certificate as "Coltheart" and has ever since been spelled that way by all of his descendants. James married Lizzie Bloomfield in Launceston, Tasmania on October 11, 1884 and they had 10 children: Clarence (1885), Daisy (1887), Elsie (1889), Sydney (1892), Frederick (1893), Lillian (1895), Clair (1896), Ann (1899), Gladys (1902) and Leonard (1906-1966). The family lived in Scottsdale, Moorina, Derby, Poimena, St. Helens, New Norfolk and Lottah where James was most likely engaged in construction related to mining operations near these towns. When the Anchor mine closed in 1913, the family moved to Longford and later to Launceston.

• Chart 83 from "A Coulthard" The history of a Surname" by Alfred Coulthart.
• Email from Max Coltheart of Sydney, Australia.
• Information researched by Neil Nicklason of Currumbin Waters, Queensland in the possession of Max Coltheart.