The adjective "kindred / akin," designating shared participation in a common nature. In the Stoics, συγγενής acquires a specific sense: human beings are kindred to one another not by blood, but by TERMintellect (νοῦς), being particles of a single cosmic Logos. The notion is the ethical correlate of the doctrine of DOGMAoikeiōsis and of Stoic cosmopolitanism: granting citizenship rights to every rational being.

SVF III 333–339 (the doctrine of the cosmopolis); Cic. De fin. III 62–68; Sen. Ep. 95.52; Epict. Disc. 1.13.3–4; 1.9.1–6. In Marcus: Med. 2.1; 3.4; 7.13; 7.22; 10.6.

In 02-01 συγγενής operates as a key transition: from diagnosis ("my neighbour errs out of ignorance") to conclusion ("I cannot be angry with one who is kindred to me"). Marcus stresses that the kinship is not "by blood or by seed," but by TERMintellect and the TERMdivine portion — a formulation that goes back to Epictetus (Disc. 1.9: "you have one father — Zeus"). See unity-of-cosmos.