It is believed that a child cannot be considered truly bilingual until he is equally proficient in both the languages. This is an impossible probability. It is natural that a child will be proficient in one language by which his normal verbal interaction is dominated. Needless to mention, the dominating language will be the one which is used by the majority people in a society in which the child lives. The dominant language is changeable according to the changes in the education, environment, age and the social network.
A child is inquisitive and learns a language by listening, observing and asking questions to adults, about what all he observes, senses and thinks about. In grammatical context, it is noun. Therefore, the Critical Period theory postulates that the second language should be learnt at an early stage. It has been found that young children can acquire better pronunciation in native language,as compared to the adult learners of the second language.
The theory of critical period has been debated upon on the following pretext. Academic language calls for specific vocabulary, grammar and the ability to converse that are required for understanding and learning better in schools. In this context, it can be said that comparatively, older students can learn their second language in a better comprehending skills as compared to younger children. Therefore, younger children can be more native-like in the long run, whereas older children can grasp grammar, vocabulary and academic language more quickly in the initial stages of language learning.
In order to acclimatize a child with bilingual environment, sometime, each parent speaks different language to the younger child. However, this cannot be the best or only way to bring up a child bilingually. Also, code-mixing cannot be reduced by so doing, but it can be stated that irrespective of what languages the parents speak, a younger child instinctively code-mixes while using the language for conversation. Therefore, parents should speak to the children in a comfortable and natural manner.