genuine (adj.)

1590s, "natural, not acquired," from Latin genuinus "native, natural, innate," from root of gignere "to beget, produce" (from PIE root *gene- "give birth, beget"), perhaps influenced in form by contrasting adulterinus "spurious." [Alternative etymology is from Latin genu "knee," from a supposed ancient custom of a father acknowledging paternity of a newborn by placing it on his knee.] Meaning "really proceeding from its reputed source" is from 1660s. Related: Genuinely; genuineness.