Mother tongue, Japanese

I watched information program yesterday. 

Several field specialist such as a neuroscience specialist, a psychologist, 
a love-science specialist and doctor　had appeared. 

They discuss about musical talent and language talent. 
According to their points, if a man does not speak mother tongue smoothly, 
it will be impossible to learn other languages. 

Man's language ability does not block to learn other languages. 

But man does not speak mother tongue smoothly, man's language ability might not be growth. 
So even if man want to learn other language, the load of learning will be hard. 


I want to learn English and other languages for communicating peoples in other countries. 
However, first of all, I should review my mother tongue, Japanese.