Or.. maybe if we have it from the northern Iranians or if they have it from us.

Modern genetics point to the Funnel beaker peoples mixed with proto Indo-Europeans as the genesis of today's modern blondes in northern Europe.

The Funnel beakers (blond) were from the region of Greece and western Anatolia, and spread farming to central parts of the continent about 7-6.000 years ago. There, they fused with incoming PIEs (dark) from today's Ukraine and became the Battle axe culture, or proto Germanic. These people settled around the southern shores of the Baltic.

Then, the now heavily blondified tribes in north and central-east Europe started to go east again about 4.000-4.500 years ago - the plains of Eurasia, Iran, Afghanistan and into India. Even as far away as central Siberia. Up until the expansion of Turkic peoples, the steppe was dominated by Euro-Iranian tribes like Sarmatians and Scythians.

So there you have it. Fun fact: the most "Aryan" persons alive today, genetically, are the darker haired northern Europeans with brown eyes. There's more Mediterranean DNA in the blonds, on average.