Buzz:  Hey, Marnie, can I ask a dumb question? How can grapes in the same family be different colors? Like, if cabernet sauvignon and pinot noir are red wines, how can sauvignon blanc and pinot grigio be white?

Marnie:  That's not a dumb question at all, Buzz. Like a lot of variations between members of the same species, it's genetic. In the vitis vinifera species of grapes that makes all of the world's best wine. The genetic norm is dark purple.

Buzz: That makes sense. The wine from the red grapes have been the most expensive forever.

Marnie: It's sort of like hair color in people, Buzz. Just as most of the world's population has brown hair, most wine grapes look blue-black on the vine. They are used for making red wines, including cabernet sauvignon and pinot noir.

Buzz:  And they all looked just like Concord grapes at the store.

Marnie:  Exactly. But after almost 6,000 years of cultivating wine grapes, there have been lots of mutations, some of which gave us lighter-skinned berries. In the same way that some people are blonds or redheads, a smaller number of wine grapes, like sauvignon blanc, have green berries. Even fewer are a weird, dusty reddish-purplish color — pinot grigio is one of those.

Buzz:   Of course! Wine growers forever are finding out how you can be creative with the grape.

Marnie: Hair color often varies within the same family, and the same is true of grape skin colors. Two genes control that purple color. When one is inactivated by mutation, the color becomes either reddish or dusky purple. If both are deactivated, though, the grapes never change color at all and stay green.

Buzz: They are using genetics to expand the possibility of looks and flavor.

Marnie:  Without both color genes turned on, there are not enough color compounds to make a red wine. The pinot family is a perfect example of how this works. The green pinot blanc grape and the dusky pinot grigio grape are both mutations of the much more ancient pinot noir grape. They're not just members of the same family. They are genetically identical with the exception of that mutation in their color genes.

Buzz:   The more flavors and colors mean a bigger audience.

Marnie:  Most people love dark-red wines now, but for centuries, those dark color compounds made primitive wines taste pretty bitter. Since green grapes can ripen better in colder regions than purple ones, farmers used to prize them in much the way we still admire blonds. So when they found a rare vine with green grapes, they'd clone it over and over again to try to get more green fruit.

Buzz: It makes sense, given that grape development seems to give us so much more than it did in the 1950s.