I will admit that I had to look up your term (which, FWIW, you seem to have misspelled). The primary
definition of “quiddities,” for the benefit of others reading this thread, is:
Humans share some “natural” traits with God. Humans are compassionate by nature (if you believe John Locke over Thomas Hobbs). Humans, by large, do not find joy in the suffering of other humans (especially innocent and disadvantaged humans, such as children and the poor).
So there is no reason to question our Lord’s Hypostatic Union (the union of his human and divine natures) based on those attributes normally associated with both natures, such as compassion for the disadvantaged innocent. But, what about those traits that are strongly associated with humans, but not with God? Such as the seven deadly sins.
BUT, are those sins
really part of human
nature? Is it possible for a human to resist (for example), greed? If it is possible, then this proclivity is NOT part of human nature (because a creature cannot resist its own “essential” nature - that’s what “essential nature” means - of the essence, and we cannot resist our own essence).
Is it POSSIBLE for a person to live an entire life without committing ANY of those evils? Or, is it possible for a human, by an act of desire, to decide at some point, that s/he will no longer be subject to ANY of them?
In other words, is it possible for a human to overcome ALL attraction to ALL sin while living on earth? The Church calls this state “spiritual perfection,” and the Church has canonized and recognized three Doctors of the Church for teaching exactly this.
Sin is NOT PART of our essential human nature. Humans can overcome all attraction to sinful behavior while yet living on earth. Many Catholic Saints have done so.
So, sin is a stain upon our human nature, but it is not a PART of it. Jesus could adopt our human nature without also adopting its stain. There is thus no
conflict between the human and divine nature of Our Lord. The two natures are completely compatible with each other.