• The most serious point in the case is the disposition of the child." What on earth has that to do with it?" I ejaculated. My dear Watson, you as a medical man are continually gaining insight as to the tendencies of a child by the study of the parents. Don't you see that the converse is equally valid. I have frequently gained my first real insight into the character of parents by studying their children.

    Arthur Conan Doyle (2012). “The Complete Sherlock Holmes: with an introduction from Robert Ryan”, p.844, Simon and Schuster