It's true about this dilution. My family is Gusii but it is well known that technically, we might be up to 50% Kalenjin, from both my mother's and father's lines. We also have substantial Luo blood. So, strictly speaking, if DNA was done, we might not get back a result that identifies us as mostly Gusii. Tis very strange. Our hair . . . has a bit of almost cushitic element going. I'm sure we don't have any cushitic mix, so I tend to assume it's from some Kalenjin ancestor.
Though I discovered last month we also border Maasai and quite a bit of intermarriage has occurred, so who knows? But hiyo ya Maasai ni guesswork. Hii ya Kakenjin and Luo is well known history from not too far back (grandparents and great grandparents, and great great grandparents) Almost all this Kalenjin and Luo blood came from what might be considered today human/child trafficking.
Another thing (also my speculation/guesswork) I think we have some Pygmy admixture in our ancestry. A substantial number of us are rather small/short. One of these days, I'll get all of us to take one of those ancestry DNA tests that are so popular these days.