According to a Meijiro University study (via Nikkei), something like 30 percent of people aged 40s to 50s use chopsticks correctly. It's said that each year the number decreases. So what's the correct way to hold chopsticks?
Before I answer that, it's important that you have chopsticks that fit your hand. If you are eating at a restaurant in Japan, you'll get standard size chopsticks, which is likely around 23cm. But, that's the typical size for men's chopsticks; the typical size for women is 21cm. However, restaurants don't usually offer a choice and just got with chopsticks in the 23cm-ish range!
Kids, however, should ideally use chopsticks of various sizes during their childhood: 1-to-2 year-olds use 13cm, 3 year-olds use 14cm, 4 year-olds use 15cm, and so on. Children around 12 or 13 use 20cm. However, most Japanese parents don't buy new chopsticks every year for their kids, and only want to when the paint on the ones they have starts chipping off or until they get way too small. When they do buy new ones, they try to get ones the kids can easily hold. And yes, one-year kids start using chopsticks to feed themselves. Using them helps with motor skills and promoted brain activity.
If you are wondering what length chopstick is best for you, you need to measure the hand you eat with. Measure the distance from your thumb to your pointer finger, so that your thumb makes a 90 degree angle where it connects to your hand (see figure). Then, take that number and times it by 1.5, and you should have the correct chopstick length.
Why does this matter? Well, if you are using chopsticks that are too small (or too large), it's far more difficult to manipulate them.
The other thing that is important is where you hold the chopsticks. The correct place to put your fingers while holding them is two-thirds of the way from the bottom. This video shows you how to hold your fingers, but basically, you are holding the top chopstick like a pencil. You will manipulate this one; however, you will not move the bottom chopstick. The chopsticks should not cross each other while you use them.
The Japanese people who hold chopsticks incorrectly are more than capable of feeding themselves—and they might look like they're doing it correctly to the untrained eye. But, perhaps they are holding the chopsticks in the wrong place or are using the wrong finger to move the chopstick. This isn't just table manner minutia. Using chopsticks incorrectly can make picking up certain food difficult.
Japanese chopstick maker Hyozaemon even has special seminars in which he shows kids how to use chopsticks. Part of that training has students hold one chopstick as a pencil and practice moving it so they can get better at manipulating it. As they get better, some of the exercises are to pick up big or difficult food, such as peanuts or small tomatoes, before culminating in soft tofu, which often falls apart easily.
Not being able to use chopsticks correctly or having bad table manners is definitely embarrassing in Japan—and it can even reflect on one's upbringing. Parents are the ones who show their kids how to eat (granted, it's ultimately up to those children to listen).
However, as research shows, many Japanese aren't using chopsticks "correctly", which gives
some breathing room to those who haven't quite mastered them or can't use them at all. For those who want to effortlessly pick up all the food Japanese cuisine has to offer, practice might make perfect.
For everyone else, just as long as you don't stick your chopsticks in a bowl of rice (there's funeral connotations), use chopsticks that don't match (more funeral connotations), or hold them like a weapon (for obvious reasons), folks probably won't raise an eyebrow. Because in some cases, who are they to be talking?