Genetics and the Aryan invasion/Out of India theories

From time to time someone tries to have settled a cultural issue through biological elements. I tend to think that this is a fallacy of false cause. Consider, in this regard, the following comment by Jan Houben on the Indology mailing list (published with his consent):

The Error was (19th cent and nazi-time Aryan Invasion Theory) and is (Out-of-India-Theory) to think that GENETICS (and racial theories) can provide explanations in cultural questions in history, such as the well-attested spread of vedism between 1500 BCE (north-west of Indian subcontinent) and 1500 AD (throughout Indian subcontinent). Many scholars have remained unconvinced and unhappy with explanations in these terms from the beginning, innumerable are those who suffered from attempts to base state implemented policies on these theories but scientific ‘truth’ is ‘truth’ and in the absence of any other explanation … As I have been arguing in several studies, however, in our understanding of the phenomenon of the spread of vedism GENETICS need not be invoked at all as a crucial factor as it is to be understood rather in terms of MEMETICS and MEMORY CULTURE taking into account vedism’s interaction over centuries with its ecological and economic environment (for instance Worries about genetic lineage became obsessively important only secondarily in the last or K-strategist (niche-exploitation) phase of vedism reflected in a relatively late work such as Manu (on Hitler and Manu see Halbfass India and Europe p 139).


What do you think? Do you trust biological explanations?