" Kees refers to "[p]arched years that I have seen," which is probably a reference to his growing into adolescence during the Great Depression and less than a decade removed from the Spanish Influenza epidemic that killed even more people than the "Great War." The author expresses concern that similar experiences "may be hers" as well, reflecting a parent's natural apprehension for the world that will be experienced by his child. In that respect, "foul, lingering" could be said to describe much of what Kees' generation would have experienced and expected for the future as they entered into adulthood. Likewise, "[d]eath in certain war" reflects the belief that the world of the 20th century was uncertain and, as geopolitical conflicts re-emerged, increasingly susceptible to even greater human tragedy and horrors than experienced in the First World War.

Kees also seems to acknowledge that despite the best efforts of loving parents, sometimes children absorb negative beliefs and cultural values and become very different types of people than their parents would have hoped. Certainly, in Kees' generation, social injustice, racism, and persecution of minorities was rampant...

In that regard, "fed on hate, she relishes the sting [o]f another's agony" is likely a reference to the capacity of negative social attitudes to infect even the most innocent creature to the extent that she becomes insensitive to the suffering of others, even enjoying their painful circumstances. The last image used by Kees reflects another fear of every father: that his beloved daughter will select a "syphilitic" (presumably a womanizer) or a "fool" for a husband and suffer the consequences of such choices despite her parent's hopes for her happiness.
Ultimately, all of Kees' concerns about the world and circumstances facing a newborn child cause any positive "speculations" about becoming a parent to "sour in the sun." This is a reference to the rationale of many people who choose not to have children specifically because they are even more fearful of the worst case scenario than they are hopeful about the event (i.e. The birth of a child) that many others consider among the most beautiful and rewarding of all of life's endeavors. Rather than leave the possibilities to chance, Kees decides that he will not take that risk: "I desire none."