Researchers have data that when parents lose their native language and cannot communicate well with their children in it, they cannot convey their values, beliefs, and experience to them. When parents are unable to communicate and influence their children due to language barriers, families can lose the closeness that comes from shared beliefs and rapport.
Oddly enough, but the native language is important for the development of foreign languages. A more developed native language contributes to the development of a foreign language. The principles in the study of foreign languages are based on this. All concepts, for example abstract ones, are laid down in their native language. An emigrant child who has begun to learn the language of the country, if not supported and developed his native language, lags behind his peers in education and experiences problems with the new language. There are many works on this topic by linguists respected in scientific circles.
Language is important to the nation. This is one of the unique identifiers of the nation, it is part of the culture of the people. The mother tongue determines how people think, communicate and express their opinions. The mother tongue is the key to a deep understanding of the culture of the nation, because no matter how well you translate, some meaning will still be lost.
What is your native language and what foreign languages do you study?