Looking at Kenyan names, we need to know some rule :
1. The name we normally use is not their FAMILY name, but is the given name in their Language. The most part of Kenyans have two given names : one English, and one in their tribal Language (so, not swahili, but Kalendjin or Kikuyu in the most part of cases).
2. Following this rule, we can say that in 90% of cases when two athletes have the same surname (or what we think is their surname....) they are not relatives.
In the cases of Kiplagat, very common name (but also surname) in Kalendjin area, we can say that EDNA and FLORENCE are KIPLAGAT as real surname, but are not relatives. Instead, LORNAH KIPLAGAT, fundator of the High Altitude Training Camp (HATC) in Iten, is cousin of Florence, being daughter of one Brother of Florence's father, while William Kiplagat, elder Marathon runner and coach of Robert Cheruiyot winning Boston and of Vincent Kipruto, is son of another Brother of Florence's father.