Ebrey states that meritocracy and a greater sense of social mobility were also prevalent in the civil service examination system, as the government held a list of all examination graduates, showing that only roughly half of those who passed had a father, or grandfather, or great-grandfather who served as a government official. However, Robert Hartwell and Robert P. Hymes state that this fact, first presented by Edward A. Kracke in 1947 and supported by Sudō Yoshiyuki and Ho Ping-ti, emphasizes the role of the nuclear family and only demonstrates three paternal ascendants of the candidates while ignoring the demographic reality of Song China, the significant proportion of males in each generation that had no surviving sons, and the role of the extended family. Male children with fathers who were incumbents in office had the advantage of early education and experience, as they were often appointed by their father to low-level staff positions. Yet with the so-called 'protection' ("yin" or "yin-bu" 荫补/蔭補) privilege this arrangement was extended to close relatives, as an elder brother, uncle, father-in-law, and even father-in-law to one's uncle could help one secure a future in office. The Song era poet Su Shi (1037–1101) wrote a poem called "On the Birth of My Son", poking fun at the situation of children from affluent and politically connected backgrounds having the upper edge over bright children of lower status: