(The prior post in this translation series is here

From the gods:
Good grandparents
Good parents
A good sister
Good teachers
Good companions
Good family
Friends close at hand

— And that I never played that false note with them, even though I have that disposition which — if by chance, the right circumstance were to arise, I would play it wrong.

Greek Text and Notes

Παρὰ τῶν θεῶν τὸ ἀγαθοὺς πάππους, ἀγαθοὺς γονέας, ἀγαθὴν ἀδελφήν, ἀγαθοὺς διδασκάλους, ἀγαθοὺς οἰκείους, συγγενεῖς, φίλους σχεδὸν ἅπαντας ἔχειν: καὶ ὅτι περὶ οὐδένα αὐτῶν προέπεσον πλημμελῆσαί τι, καίτοι διάθεσιν ἔχων τοιαύτην, ἀφ̓ ἧς, εἰ ἔτυχε, κἂν ἔπραξά τι τοιοῦτο:
οἰκείους: in the vernacular, homeboys
σχεδὸν: close, near, hardby
πλημμελῆσαί: to play the wrong note; and thus by metaphor to offend or sin against. Being in the infinitive it shows the result or purpose, the outcome of the wrong fall.

διάθεσιν: placing in order, arrangement
ἀφ̓ ἧς: from her. Nearest antecedent: τοιαύτην: which refers back to διάθεσις
Therefore, from this disposition. From her (this disposition) as a source. Cf. 1 Cor. 11:23.

εἰ ἔτυχε: if it chanced

κἂν ἔπραξά τι τοιοῦτο: if it might be that it happened such a thing such as this. I would do that bad thing.