What is the ideal age to learn a foreign language?

According to research, learning a new language is similar as learning the first for kids. Since children have a natural ability to learn and this is developed in the first 3 to 4 years of life, they can start learning at the age of 3! It is proven that 50% of our ability to learn is developed by age 4 and another 30% by age 8 which supports the idea of teaching kids as early as 3 years old.