Bilingual children's acquisition of their heritage language very much depends on their parental language input patterns.One study carried out by De Houwer (2007) to investigate the reasons for some children raised in a bilingual setting can speak two languages and others cannot. A Total of 3,677 parents and 4,556 children in 1,899 families participated in this study in Belgium, where Dutch is the dominating language. The participants came from different ethnic groups and spoke different languages. The results demonstrated the function of the parental language input patterns, in families where each parent spoke just heritage language, and those where one parent spoke only heritage language and the other one spoke both heritage language and Dutch, having more chance of raising children who spoke the heritage language well. Therefore, bilingual children's acquisition of their heritage language very much depends on their parental language input patterns. De Houwer (2007) also reported that parents' language beliefs and attitudes might determine children's pattern of language use in crucial ways; negative attitudes to a particular language will keep some bilingual speakers from using that language with their children. In order for early active bilingualism to develop, parents need to have least a positive attitude to both languages involved and to early bilingualism, and a positive belief in impacting their children's language learning.
De Houwer, A. (2007). Parental language input patterns and children's bilingual use. Applied Psycholinguistics, 28, 411-424.