Dinka and Nuer are more related to Luos than Kalenjin. Kalenjin are very different from other nilotes. The reason is coz Kalenjin moved out of Nile very long long time ago. Maasai are related to turkana, teso, karamojong, toposa and the guys in Juba (maasai cousin lotuko) --so I would say whole of eastern equitorial - is turkana-maasai-teso like people. The western part is Kuliak (Amin people) -- all the way to congo--and northern is Luo and their cousin Nuer & Dinka.
Kalenjin are totally different from any south sudanase tribe --and the nearest I've come close to Kalenjin like people are maybe the omotic people who speak cushitic language.
I think the reason why Kalenjin are different is because they were 1)northmost of nilotes while living in Sudan and 2) move out of area around Khartoum earliest 2,000-4,000 years before the next nilotic group would move out--and they moved together with proto-cushitic people---way before Islam even arrived in Sudan...so Kalenjin got cut off, lived in Ethiopia, Kenya and Tazania...with cushites and Khoisan (okiek-dorobo).
Maasai and eastern nilotes (turnaka, teso, toposa) would move 2,000 yrs after Kalenjin have to East Africa...spreading pure pastoralism and fighting like crazy and kicking everyone out of their way.
Luos moved recently...500 yrs ago to Uganda and Kenya....I think running away from islamic/arabic slave traders and after conflicting with their cousins shilluk...seem they followed river nile till it sources in Lake victoria...leaving their people along the nile river in most of uganda.
When Luo next found themselves near the other nilotes in Kenya..it was the Kalenjin...who they reffered to as Lango -- which is what I reckon they would 'cousin'...but the re-union was a long one -maybe 4,000 yrs being apart.
Not Luos as some claim. Luos relatives are the Shilluk whose role is minimal
The Dinkas and Nuers are closely related. That means the trouble-makers are all "Kalenjin".