In their innocence Sholes and his partners first arranged the letters of the typewriter's keyboard in alphabetical order, but the uselessness of this system soon became apparent. ... You didn't have to type very fast for the letters to rise up and jam at the platen (the roller of a typewriter), the very place where they were supposed to print. To end that annoyance, James Densmore asked his son-in-law, a Pennsylvania school superintendent (who surely should have known), what letters and combinations of letters appeared most often in the English language. Then, in 1872, Densmore and Sholes put what they believed to be the most used characters, as far apart as possible in the type basket and ended up with the horror of qwerty. -- Charles Lekberg: "The Tyranny of Qwerty", Saturday Review of Science, Vol.55, No.40 (September 30, 1972), pp.37-40.
Mr. James Densmore had no son-in-law in 1872. His only daughter, Miss Tina Densmore, married with Mr. Edward Joseph Delehanty in Greenville, Pennsylvania, on July 23, 1874, thereafter, Mr. James Densmore got his son-in-law. Mr. James Densmore couldn't ask his son-in-law anything about the English language before the first "Sholes & Glidden Type-Writer" was manufactured in 1873 with the original QWERTY keyboard (shown below, taken from U. S. Patent No.207559).