What could cause milky green dual nipple galactorrhea in a male with normal prolactin levels? ongoing since age 13. nipples are never stimulated.

Not worrisome: It sounds like this has been going on for a while (12 years). That, and the bilaterality, suggest that this is not something you need to be worried about. Figuring out what the cause is harder. Are the breasts enlarged (gynecomastia)? Are there any medications? Has anyone confirmed galactorrhea (not all discharges contain milk). Assay for altered forms of prolactin (macroprolactin).