One begins to understand the puzzled reaction of those new to the region, such as a visiting Sudanese intellectual:
'I had come to know, more or less, the stereotypical description of the short Negroid Hutu and the tall, fine-features Hamitic Tutsis. As I looked at my audiences, I saw a few who were clearly Tutsis and a few who were clearly Hutus. But most were somewhere in between, and I could not identify them. I later asked the Burundese, including senior government officials and ministers, whether they could tell a Tutsi from a Hutu. The response of the Foreign Minister, which represented the general tone, was a confident ‘Yes,’ but ‘with a margin of error of 35 percent’—a remarkable margin given the confidence of the affirmative answer.'
‘There’s been so much inter-marriage over the years that you often cannot tell who’s who,’ said a presidential aide from Burundi to a Western reporter, and then added as an afterthought, ‘but everybody knows anyway.’
I have been unable to find comprehensive data on the extent of inter-marriage. Yet, all accounts I have heard of or read speak of considerable intermarriage: anywhere from a significant minority to a majority of contemporary Rwandans are likely to be children of Hutu and Tutsi intermarriages over the centuries. This means that we cannot equate the identities Hutu and Tutsi with those identified as Hutu and Tutsi when this process set in motion. Rather than being biological offspring of Tutsi of centuries ago, today’s Tutsi need to be understood as children of mixed marriages who have been constructed as Tutsi through the lens of a patriarchal ideology and the institutional medium of a patriarchal family.”
by Mahmood Mamdani “When Victims Become Killers: Colonialism, Nativism, and the Genocide in Rwanda” p 53-54