Neuromyth...

“A young child’s brain can only manage to learn one language at a time”
"The myth that one has first to speak well one’s native language before learning a second language is counteracted by the studies showing that children who master two languages understand the structure of each language better and apply them in a more conscious way. Therefore, multilingualism helps foster other competences related to language. These positive effects are clearest when the second language is acquired early; a multilingual education does not lead to a delay in development. Sometimes, very young children may confuse languages but unless there is a defect in acquisition, this phenomenon later disappears".
In reading the myth immediately remembered my cousins kids, which since the birth of her parents have spoken in English and Spanish and since has 6 years beginning with a bilingual kindergarten, and then enter the school "the newland school”, where English is learned principled rather than the same Spanish. Today they speak both languages perfectly. On the other hand, I remembered a friend, the daughter of Chilean parents, but lives in France, from childhood was in contact with both languages, so now both easily mastered according to the need you have. None of these three people that I took as an example, have problems with neurological development or language, by contrast, are people who are doing excellent in school and healthy.
In the case of any confusion in relation to languages, the best example of me, because when I was a child attending a school where they teach us Italian, then I move to town, and began attending a school where he taught German, and returning to Santiago, I came to a school where he taught English, and at home they speak Spanish, therefore, with so many changes, I could never master one, and that confused me from the start.

After these examples, I can be sure that I completely disagree with the myth, I even think that learning more languages, helps develop more our brains and skills.