I don't really want to step into the middle of this because I am nowhere near as intimately acquainted with Persian culture as LibreOuMort, but this statement really set me back. It runs quite counter to my knowledge of Iranians here over the past quarter-century.
According to an excellent book: "The Arab Mind," by Rafael Patai, the Arab culture has a perspective on reality that is significantly different from the Western, to a degree that where we see blatant lies, they quite literally see a different reality. (Patai says, as I recall, that this is a result of the exceptionally high degree of expressiveness of the Arabic language -- sort of what we might experience if our everyday street/business English came straight out of Shakespeare.)
But the Persian culture and language is very different from the Arabic. I have yet to meet a Persian who has kind words for the Arabs, especially those who rule Iran today.
My knowledge of Iranians here is admittedly limited, and there are likely those who have become somewhat "Arabic" but those I know personally do not possess this Arabic sense of "truth," they're quite a bit more Western in this regard.
I have not encountered any evidence that (what we call) lying is a part of Iranian culture. Arabic, yes; but Iranian, no.
Do you know any Americans dating any Iranians or marrying them?
Out here, my sister wasn't the only case. When I would bring up the story of my sister in conversation, I would almost always get back that they at least know someone who had the same experience.
Like I said, best to stick to marrying Americans. Anyone of any nationality that are born here are more likely to be equally yoked with you.