Born in Wimbledon, Surrey, Thomas Ralph Merton was the only son of Emile Ralph Merton and Helen, daughter of Thomas Meates, a descendant of Sir Thomas Meutas, Secretary to Sir Francis Bacon. Emile Merton was for a time in the family metal trading business as a partner in Henry R. Merton & Co. which was started in London by his eldest brother in 1860. Another brother William Ralph Merton founded the Metallgesellschaft in Frankfurt-am-Main in 1881, which became the second largest company in Germany and the largest non-ferrous mining company in the world. The two companies worked closely with one another, along with the American Metal Company in New York City.