to share the same ancestry and have common roots

(linguistics) Two or more words in a single language that come from the same original source word but have different forms and meanings.

cognate; paronym; doublet; words having a common origin

Describes different groups, sects, or schools of thought that share a common origin or fundamental basis

literally food and medicine share the same origin; an idiom or health philosophy suggesting that diet and medication are indistinguishable and that proper food choices can maintain health and prevent disease