The owner and Gigi (the sommelier) are half-brothers, and also cousins—the owner's father had an affair with *his* brother's wife. As a result of the affair, Gigi and the owner didn't meet until they were in their twenties, when they hit it off well, and decided their fathers' feud had nothing to do with them. Gigi observes people closely – it's how he's able to pick just the right wine for them – so he's figured out that Nicoletta is Olga's daughter.