About 16 years ago a DNA test showed that Cabernet Sauvignon is a cross between Cabernet Franc and Sauvignon Blanc. Vine breeding wasn’t well understood when Cabernet Sauvignon showed up in the 17 century so it’s likely it was unintentional. The result of cross breeding Cabernet Sauvignon has been linked to other varietals. A cross of Cab Sauvignon and Grenache produced a French wine grape called Marselan. With cross breeding it’s no surprise there are over 10,000 varieties of wine grapes in the world.