To discuss why Marcus Aurelius' father is described as having "manliness and integrity", even though he left his son at an early age?
well that's a translation and cultural problem! Manliness and integrity had completely different meanings in the classical world, particular amongst the Italianate aristocracy of the Roman empire... your confusion reflects the monumental, cultural sea-change that occurred between the battle of the Milvian bridge and the deposition of Romulus August in the west. Please read Gibbon's classic book on the subject.
Anyway, this profound difference in meaning and point of view carried over into Macchivalli's writing in which he uses the term 'virtue (ital. virtu)' incessantly in its classical sense (latin: virtus, direct ENGLISH translation manliness, though like the latin words auctoritas and dignitas, no single English word can convey the culturally alien meaning of any of these latin words), not its post-Christian sense and in doing so confused students reading English translations of the Prince for generations.... even though the big M was writing in the vernacular, given the minimal influence of Germanic languages on the development of modern italian from latin, some Italian words still carry a bit of the pre-Christian meaning of their latin roots, and in the case of virtu AKA manliness, Nicollo is still leaning heavily on the meaning of the words latin origin.
Because you are reading a translation of Marcus, you are having a pretty typical issue with the text. Without breaking out my latin copy (and struggling to find the page you are talking about with my VERY rusty latin) I want to say that I think the word Marcus selected was Virtus and it has been translated in your copy as 2 English words, manliness and integrity. I don't think I I would translate virtus that way, especially in this context and especially not for a modern American reader. Its easy to want to translate Virtus or Virtu as manliness given that the root of this adjective is the latin noun vir, or man. But even that noun has a deeper sense than our modern English noun. Rather than 'man', in most texts try looking at the word vir as "real man." However, while there is an element of what we would call machismo, there is an even stronger streak of civic duty....
I take it you're reading "meditiations" for the first time? If you can read ANY Latin I encourage you to get the version from the Loeb Classical liabrary that ahs Latin on one side and a solid English translation on the opposite page and try to muddle through that way. To take a page from Marcus himself, really reading the classics is more like wrestling than dancing ;-)
here's the quicky entrance into the wonderful world of the ancients: http://www.hup.harvard.edu/features/loeb/digital.html