One day in April 1809, over three years after the death of William Pitt, the prolific diarist Joseph Farington relayed a curious story Hoare told him about Pitt's precocious childhood:
"He [Hoare] told me that Lord Chatham [William's father], when at Bath, had intercourse [friendly conversation] with His Father, & was so much pleased with the regularity He saw in His family as to express His approbation of it, and desired Mr. Hoare to send His Sons to play with His (Lord Chatham's) Sons, which they did frequently at His Lordship's House in the Circus. The late Minister, William Pitt, was at that time Seven or Eight years old. He [Pitt] often quarrelled with the other Boys; and, while at play, was, on that account, put into an adjoining room, from whence He issued while they were playing at marbles, & with a large taw marble, He drove through their game. His Father, at that early age, was accustomed to take Him into a room and there debate with Him - and His young mind was then so filled with ideas of Oratory that one day while these Boys were walking upon Combe [sic] down near Bath with Mr. Wilson, tutor to Ld. Chatham's sons & afterwards Canon of Windsor, Wm. Pitt said, "He was glad He should not be a Lord." On being asked by Mr. Wilson why He said so, He replied, "Because He could not then be in the House of Commons & make Speeches like His Father." 
This anecdote dates from 1766, when William Pitt the Elder was elevated to the Earldom of Chatham. Young William was seven years old, and highly sagacious, if not impressionable. Indeed, on August 2, 1766, Mr. Wilson wrote to Lady Chatham to the same effect, conveying William's relief at not being the eldest son as "he could serve his country in the House of Commons like his Papa." 
I wonder what instigated the arguments with Hoare's sons? Boys will be boys.
1. Greig, J. (ed.) (1923) The Farington Diary, Vol. 5. New York: Doran, p. 141.
2. Taylor, W.S., and Pringle, J.H. (eds.) (1838) Correspondence of William Pitt, Earl of Chatham, Vol. 3. London: John Murray, p. 27.