На Еупедији се водила интересантна расправа између Маћама (Maciamo Hay) и неких Бошњака који су му упорно доказивали да су R1a Словени, а I2a Илири, на шта је он одговорио:
"I think that the problem is that you do not understand that haplogroups evolve over time. Each mutation point back to a particular period in time. I1 and I2 (not I1a and I2a) separated 25,000 years ago, but nobody (I mean really absolutely not one individual) belongs to I1* or I2* today. Everybody belongs to deep clades under these haplogroups. When we refer to I2 members today, we mean all people who descend from that common I2 ancestor.
When haplogroup R1a was formed, it was a North Eurasian lineage. When the M417 mutation appeared 8,500 years ago, it was part of a Mesolithic Eastern Europe. It was obviously neither Slavic not Germanic at the time, because these languages and ethnic groups didn't exist back then. Even when descendants of R1a-M417 started spreading across central and northern Europe 5,000 years ago with the Corded Ware culture, these people could only be called Proto-Indo-European. There were no Slavs, Germans or Indo-Iranians back then. But it's around that time that mutations like L664, Z284, M458, etc. appeared and formed new ethnic groups by mixing with the indigenous people in each region. Yet, even one thousand years later, there were still no Slavic or Germanic ethnic groups. At best we could start to talk about pre-proto-Slavs and pre-proto-Germanics. It's only around 3500 to 2500 years ago, during the Nordic Bronze Age, that the Germanic ethnicity started to take shape, when R1b-U106, R1a-L664 and I2a2a-L801 from Germany moved into Scandinavia and mixed with the I1 and R1a-Z282 populations there. Before that I1 and R1a-Z282 cannot be called Germanic, because their carrier didn't speak an Indo-European language ancestral to modern Germanic languages. This language was the merger of Bronze Age IE language from what is now Germany and Scandinavia. The Slavic ethnogenesis happened even later.
To answer your last question, I never said that I2a was a Slavic haplogroup. It's a Mesolithic European haplogroup. It is I2a1b2a1-CTS10228 that is Slavic, and only that subclade, because that mutation emerged exactly during the Slavic ethnogenesis in Eastern Europe, and it spread to all Slavic-speaking countries with ancient Slavic migrations. Note that this CTS10228 is not found only in the Dinaric Alps, but in all Slavic countries, and that it can be calculated relatively accurately that all people who are I2-CTS10228 descend from a common ancestor who lived only some 2300 years ago. That's why it cannot be Illyrian.
I don't know what were the haplogroups of Illyrians. It wasn't a single haplogroup for sure, but I'd bet they carried some R1b subclade older than P312 and U106 (e.g. L51 or L11), because it was the R1b branch of Indo-Europeans that settled in Southeast Europe during the Bronze Age."