Grant was born in Strathspey, Scotland, along with John Small. Grant's wife Sarah (1743-1807) came from the well-known Bergen family of New York, who descended from Hans Hansen Bergen.[1] They married on August 30, 1759 in New York and had 12 children.[2][3] They attended The First Reform (Dutch) Church, where they were married and many of their children were baptised.[4][5] Portraits were made of both John and Sarah but their location is unknown.[6] Sarah was the daughter of Meighiel (Michael) Bergen and his first wife Femmetje (his second wife was Catelyntie).[7] In 1767, Bergen lived on the south side of the town of Jamaica, Queens, his mill was on a pond in present-day Springfield Gardens, Queens. Because he was a loyalist, Bergen eventually requested protection from Britain.[8] After their marriage, John and Sarah settled on Bergen's farm in Queens. Bergen left money in his will to John and Sarah's oldest son, Bergen's grandchild, Michael Bergen Grant.[9]
He arrived in Nova Scotia on the transport HM Berwick, 1 July 1783 after evacuating his home in New York.[15] He brought to Nova Scotia 7 of his children and 9 slaves, all of whom were buried on his property. Captain John Grant died in Summerville in 1790 at the age of 61. The Grant homestead was on what now is called Loyal Hill.