According to Wikileaks the Saudis hard-pressed the U.S.A to attack Iran “right now”. Arabs seems very afraid of the growing Iranian influence in the region and the Iranian nuclear program. Apparently the Americans refused the idea based on geopolitical stability calculus.

Iran is already supporting insurgencies in Iraq and Afghanistan, i don’t think they mind US weakening the Taliban and Al-Q in Afghanistan, except for the fact that right now all they see around them are US military bases (Saudi, Iraq, Afghanistan etc.).

That’s basically untrue. Taliban are declared enemies of the Shiite Islam mostly practiced in Iran. In addition the Iranians performed some small scales punitive actions in Afghanistan after the Soviet retreat and before the NATO intervention. There is no way the Taliban to be considered Iranian puppets to perform a proxy war.

In Iraq, the situation is different. While Iran may economically support Shiite militias they are holding them as “strategic reserve” for asymmetrical answers just in case an American attack. So, they are likely providing arms and some degree of training but on condition to put them on hold to unchain at the “right time”.

On the Iranian population, even, considering the small Arab influx with the Islam, most populations seems to have preserved the Indo-European lineage. According Cavalli-Sforza (Genes, Peoples, and Languages) there is no significant genetic difference between Persians and Europeans. Interestingly the Arabs are not the most numerous minority. The most numerous minority is constituted by the Azeri (It is a people with a Turkic origin).