The word of the day is cognate:
1. related by birth; of the same parentage, descent, etc.
2. Linguistics. descended from the same language or form.
3. allied or similar in nature or quality.
c.1645, from L. cognatus "of common descent," from com- "together" + gnatus, pp. of gnasci, older form of nasci "to be born" (see genus). Words that are cognates are cousins, not siblings.
"It was plain to see that these three religions all share historical antecedents with Nigerian Yoruba and Beninese Fon religions. They are clearly cognate religions."
- Henry Louis Gates, Jr., Black in Latin America