While ambidexterity is a rare trait, it is more uncommon to be able to write at the same time in two different languages. Chen Siyuan, of China, is proof of a "rare trait of a rare trait."
When you are born, you will be dominant in one hand than the other. In most cases, you can be born right-handed. With respect to many sports, especially combat sports, you have more right-handed athletes than left-handed athletes. Think of yourself as a amateur or professional Boxer for example. If you were right-hand dominant, you would most likely be trained to fight in the orthodox stance as your right hand would be your power hand and your left hand would be your speedy jab hand. If you were left-hand dominant, you would most likely be trained to fight in the southpaw stance. There are cases where you are left-hand dominant and would be trained in the orthodox stance. That way, your power hand comes out faster.
In the case of other sports such as Judo, Karate, Muay Thai, Tae Kwon Do, etc, you would be more proficient in one side than the other when doing certain moves. It's rare to see professional fighters be able to effectively change back and forth between orthodox and southpaw. Keep in mind, right-hand vs. left-hand dominance doesn't just apply to combat sports. This can be applied to many different vocations, hobbies, and so forth.
Take writing and calligraphy for example; you may find yourself proficient using one hand than the other. In the case of the other hand, it comes out all sloppy because it takes time getting used to. You have to factor in muscle development, muscle control, brain responses, and so forth. That's because you're having to train both your brain and your muscles.
This can be compared to someone in martial arts learning to kick with the front leg. In most cases, many martial artists are usually trained to kick with their back leg instead of their lead leg for maximum power.
There are those that possess the rare trait of ambidexterity. Being ambidextrous can mean that you are able to effectively use both hands. In terms of writing, you are able to proficiently use both hands to write.
One should take a look at 24-year-old Chen Siyuan or Siyuan Chen. Remember that in Asia, the person's last name usually goes first and the first name usually goes last. She possesses the trait or rare gift of ambidexterity. However, ambidexterity alone isn't something that would get a person's attention. But, there is something special that Chen has achieved using her ambidextrous skills. At the moment, she has achieved something that other ambidextrous people may not be able to yet.
What is this special sub-trait of Chen's ambidexterity?
Chen is able to proficiently write in two different languages at the same time. In a BBC News report, Chen has used this when writing poetry. She can write constructive sentences in one language using one hand and write constructive sentences in another language using the other hand. In Chen's case, she's writing in Chinese with one hand and writing in English with the other hand.
When interviewed by People's Daily Online, Chen said that this did not come from hours of practice. It came out of necessity. That necessity was dealing with being able to finish homework on time. To Chen, this came as a passive rather than active ability. An analogy of this concept can be compared to video games in which your characters have a special ability which can be passive. That means, they don't need to be activated. In the case of Chen, she didn't have to active that ability.
Furthermore, as reported by People's Daily Online, Chen said that classmates tried to imitate her. However, all of them failed.
So far, one can analyze and think over how Chen has been able to be able to write in two different languages simultaneously. There are so many different variables you have to think about. Plus, you have to think about the relationship with the physical (your body) and the mental (your brain).
First, imagine yourself trying to write with your other hand. Second, once you've done the first, imagine yourself trying to write simultaneously with both hands. Third, if you've thought the second was difficult enough, imagine having to use one hand to write in Japanese and the other hand to write in Russian at the same time.
A talent like that could give “Ripley's Believe It Or Not” a run for its money.