Franklin also had an extramarital son, William (born c. 1730–31),[5] whose mother may have been a maid in the household,[6] perhaps a woman named Barbara,[7] or even Deborah Read herself.

[17] Given that Franklin considered Francis to be a "healthy child who thrived from the start,"[18] and "very clever," he advertised for a tutor for his two sons in December 1734.

[20] By 1734, Franklin's business as a writer, publisher and founder of the Library Company of Philadelphia was going well enough that he was able to build a house for his family of four, at 318 Market Street.

[26] Franklin had written his paper "On the Death of Infants" while Francis was still alive and was inspired by his youngest son when writing about the beauty of babies.

After Francis' death, Franklin became involved in promoting inoculation in Philadelphia: he published many studies on its value, working with several physicians, including the famed William Heberden at the Pennsylvania Hospital, which he helped found.

This I mention for the sake of the parents who omit that operation, on the supposition that they should never forgive themselves if a child died under it; my example showing that the regret may be the same either way, and that, therefore, the safer should be chosen.

Franklin replied that it "brings often afresh to my mind the idea of my son Franky, though now dead thirty-six years, whom I have seldom since seemed equaled in everything, and whom to this day I cannot think of without a sigh.