Maybe getting red wine stains on your teeth would be less embarrassing if it was a universal experience. But as you may have noticed after splitting a bottle of cabernet between friends, wine doesn't have the same tinting effects on everyone. Whether vino leaves your teeth untouched or makes you look like you've been chewing on a purple Sharpie, you can give credit to your genes and hygiene habits.
A mix of components make red wine the perfect drink for staining teeth. It's acidic, which means it degrades your enamel at the microscopic level, making the surface of your teeth less even and more likely to catch pigments. Red wine contains anthocyanins, the pigment that gives wine (and the mouths of some wine-drinkers) a dusky red color, as well as tannins, which encourage those pigments to bind to your teeth. White wine also has acid and tannins (though a much lower level of tannins than reds), but without the dark pigments, drinking white wine alone won't stain your teeth.
Some wine drinkers are better equipped to handle this than others, such as those gifted with healthy, strong enamel. Enamel is the layer of minerals that protects your teeth, and it's the strongest substance in the human body. It's what makes teeth resistant to acidic foods and stains, and how much of it you have is often a product of factors beyond your control, like age and genetics. (Enamel doesn't grow back, so it wears down over a lifetime of use.)
But even if your genes are working against you, that doesn't necessarily mean you have to choose between your favorite drink and a presentable smile. You can prevent wine mouth, or at least make it look less noticeable, by practicing good oral hygiene. Teeth covered in plaque are more likely to stain, and brushing your teeth at least twice a day and flossing daily helps reduce plaque while keeping your enamel strong.
If you plan on ordering red wine at the bar you're heading to, brush your teeth beforehand: This will get rid of a lot of the plaque that would otherwise act as a magnet for pigments. Because brushing can scratch enamel in the same way that acid does, this should only be done about 30 minutes before you have your first sip of wine, and not in between glasses. Eating while you drink can help as well. By munching on a protein, you can create a sort of stain-blocking barrier for your teeth—just in case you needed an excuse to order a cheese plate with your pinot.
What you choose to drink also factors into how stained your teeth may or may not be by the end of the night. Though wines like chardonnay don't stain your teeth, they do make them more vulnerable to dark pigments, so never start off drinking white wine and move on to red. Dark wines tend to leave the darkest stains. If you absolutely must have a glass of red wine with dinner, opt for a pinot noir over a cabernet (or something lighter-bodied, in wine-speak).