Razib at Gene Expression, using the results of a whole genome DNA test performed on an individual who is self-identified as 1/4 Hutu and 3/4 Tutsi does a two part comparison of this individual's DNA with that of other known populations for which data is available. The existence or lack therefore genetic differences between Tutsi populations and Hutu populations is one of great historical and current political interest, but no extant whole genome DNA studies have publicly available data for Hutu or Tutsi individuals.
Tutsis and Hutus are found in Rwanda, where the distinction became know to the world as a result of the attempted genocide of Hutus seeking to slaughter all Tutsis, and Burundi, as well as some neighboring countries. There is a long history, at least dating to Belgian colonial involvement, of minority Tutsis serving as a ruling class that presided over Hutu majorities, and of mass slaughter between these peoples who speak the same language, who share the same religion, and whose visible differences in appearance from each other can be subtle to people not attuned to them (both groups would be considered "black" in either the American or Latin American vernacular racial classification schemes).
A core question in relation to these ethnicities are whether they are a caste system, possibly created by the Belgians from a common population, or the result of once ethnically distinct separate communities that have merged in a way that produced these results. Razib reached the latter conclusion.
He concludes that a Bantu speaking peasant farmer population from Kenya is a reasonable proxy for Hutus and that this individual's DNA is in contrast with the proxy strongly suggestive of a Tutsi gene pool very similar to the pastoralist Masai, the best known of the Nilo-Saharan linguistic pastoral peoples of Africa. He theorizes that the Tutsi people were an intrusive pastoralist people who came to rule the antecedent Hutu farmers of the area, probably prior to significant European colonialist intervention, which is a common historical pattern, but that the Tutsi eventually lost their language to that of the Hutu people whom they ruled.
As an English speaking American of South Asian descent, of course, he is not a personal participant in the controversy and comes to the issue with a relatively open, albeit informed, mind. And, the full posts are full of caveats associated with the single genome data set, the limits of the methodology, and the importance of not make assumptions that amount to Platonic ideals in the admittedly inexact matter of looking for large scale population scale where the predominant factor is admixture of previously more genetically distinct populations.