Originally Posted by
Demetrios
That's not totally accurate. Indeed the Neolithic Balkans were predominantly G2a (some 57%), but we also had some minor I2a presence, though certainly not I-Y3120 which came later. You can see some interesting pie charts in these following Eupedia articles, about Europe in general:
Not surprisingly, the Megalithic cultures in western Europe were almost exclusively I (84 samples), while they also had very few H2 (3 samples). I suppose you meant to write, present in central, further west and north-west Europe.