Robert John Abercromby was born 14 June 1850 in London and became the seventh Abercromby baronet on the death of his father at the end of 1872. His inheritance included the family estates of Birkenbog and Forglen as well as land in Ireland. The main family seat was Forglen House situated to the north west of Turriff in Aberdeenshire. He was Deputy Lieutenant of Aberdeenshire and Banffshire and was also a Justice of the Peace in both counties. Commissioner of Supply was another role he fulfilled.
Abercromby was the son of George Samuel Abercromby (1824–1872) and Agnes Georgina, who was the daughter of John Cavendish, 3rd Earl of Kilmaine. The couple had three other sons, George Cosmo, Cavendish Douglas and Douglas Charles. They also had two daughters.
Abercromby was born in London but as his father succeeded to the family estates in Scotland and Ireland during 1855 when Abercromby was five years old, his formative years were spent at Forglen House. He was educated at Eton College. In November 1872 Abercromby inherited the estates from his father becoming the 7th in the line of Abercromby baronets.
The main family seat was Forglen House in Turriff, Aberdeenshire and he continued to make improvements to the house and policies that had been initiated by his forebears. The Abercromby's also owned land in Ireland as his grandfather, Sir Robert Abercromby, 5th Baronet, had bought most of the town of Fermoy from fellow Scotsman John Anderson during the first quarter of the 19th century. Robert John Abercromby, 7th baronet, is recorded as the owner of 434 acres of land in County Cork during the 1870s. and Fermoy House is listed as the family seat in Ireland.Inchdrewer Castle also formed part of his inheritance and MacGibbon and Ross list it in his ownership in 1887.