By focusing on a crucially different notion of the critical period for language, with a crucially different time scale: that of a critical period for first language acquisition. A study approached this question in examining the language outcomes of children who missed their critical period for acquiring a first language: children who did not receive the required language input because they grew in isolation. The acquisition of syntax in a first language has a critical period that ends during the first year of life, and children who missed this window of opportunity later show severe syntactic impairments. 

Several cases of children who grew in isolation and experienced drastic deprivation of language input during the critical period for first language acquisition are reported in the literature. These children later failed to acquire language even after exposure to language and sometimes formal language teaching, and their main domain of difficulty was morpho-syntax. The cases of Genie and  Cambodian jungle girl are known examples of impaired language acquisition following deprivation of language input during a critical period. 

 Genie also failed to construct sentences derived by syntactic movement. This demonstrates a crucial point regarding critical periods for first language acquisition: different language domains may show different acquisition paths, with different critical periods and some may not be constrained by critical periods at all. Syntax, and specifically syntactic movement, are affected by lack of language input early in life, whereas single lexical items may still be acquired once language exposure begins or resumes. Genie’s language was thoroughly studied. Not all later studies of isolated children explored various domains of their language and specifically syntax, but the pattern seems to be similar: whereas single words can be acquired later in life, syntax can no longer be acquired normally This suggests that language input during the early years of life is crucial for the development of syntax.

(Cambodian Jungle girl)
In another case of Rochom P’ngieng or known as a Cambodian jungle girl, she was lost in the Cambodian jungle for eight years and was found at the age of 29. Rochom P’ngieng was lost in the jungle of Ratanakiri province, Cambodia, at the age of eight when herding buffalo with her six-year-old sister who also disappeared. She was discovered on 13 January 2007 after a villager noticed some of his food had been taken. He staked out the area and sighted a naked woman stealing his rice. Then, she was recognized by her father, policeman Ksor Lu long, because of a scar on her back. The girls probably lost their way back home and kept wandering in the woods.

Rochom was unable to speak any intelligible language. After spending almost 19 years in the jungle, the girl forgot all vocabulary and could only speak three words: ‘mother’ ‘father’ and ‘stomachache’. Besides, there is a difference between Genie and Rochom where Genie never communicated with humans for her whole life but Rochom might be used to it before she lost at the age of 8. Thus, she is considered to have faced the first language acquisition even though she already passed the critical period like Genie. However, she is still unable to acquire language fluently and syntactically because of the long-term period of isolation without human exposure.

After about five months, Genie acquired enough vocabulary to produce single words spontaneously and was able to express emotions. Meanwhile, Rochom enables to understand a few words in Khmer and ethnic Phnang language but is unable to reply.

Although Rochom P'ngieng doesn’t speak normally and is only able to say a few words through her progress in rehabilitation, she knows how to do a lot of things and especially talking to herself in her animal-jungle language that others cannot understand. The ‘Animal-jungle language’ is an advantage for her to communicate with nature.

That is a critical period, during which they can best acquire language. The later the language is learned, the less it will be native-like. Genie, for instance, who was exposed to the language after puberty, was skilled at basic word order and grammar but was awkward with its morphology.

Both of them were not having two-way communication well enough as Genie was never exposed to humans while Rochom was isolated in the jungle for a long-term period. Thus, this makes them lack language development and only the right brain function to raise the possibility in acquiring language. 

Model behavior in childhood: https://www.canr.msu.edu/news/monkey_see_monkey_do_model_behavior_in_early_childhood

(Google Scholar) Research about relation between sociocultural theories and second language acquisition:
https://hrmars.com/papers_submitted/3747/Sociocultural_Theories_in_Second_Language_Acquisition.pdf

Sociocultural theories differ fundamentally from other perspectives in second language acquisition because of their understanding that social environment is not the context for, but rather the source of, mental development (Swain & Deters, 2007). Whereas other perspectives focus on an individual and what the individual is doing, SCT takes into account the complex interaction between the individual acting with mediational means and the sociocultural context (Lantolf & Thorne, 2007). In other words, sociocultural theories emphasise what tools the person is acting with, where the action takes place, and why the person is acting (Swain & Deters, 2007).

(Youtube) Sociocultural factors of second language acquisition:
https://youtu.be/WEB5CobZYG8

 For one, helping others feels good: it often leads to a positive mood and reduced stress. Over time, prosocial behavior is associated with greater psychological well-being, better social relationships, and better physical health, including greater longevity. Thus, prosocial behavior is valuable for both those who receive help and those who do the helping

Research has found that engaging in prosocial behaviors helps mitigate the negative emotional effects of stress. Helping others may actually be a great way to reduce the impact of stress in your life.

second language appears to be the most factors that affect second language acquisition. There is a strong relationship between learners' behavior toward the second language and success in second language acquisition. Behavior is a series of values that play an important role in the acquisition process. The learners' positive  behavior encourages  learners to make serious endeavors to acquire the language. On the contrary, negative attitudes detain learning. Competence of a second language is reached  when there  is an ability to be in continuous contact with the second language. This continual contact depends 

on the learner's attitude toward the second community

Labov do the social stratification of /r/ in three department stores. It is Saks Fifth Avenue (highest), Macy’s (middle) and S. Klein (lowest). He gathered the data through interviews and used the formal speech in the interview. The results are 62% of Saks, 51% of Macy’s and 20% of Kleins. Those with higher socioeconomic status pronounced /r/ more frequently than those with lower socioeconomic status.

The use of nonstandard -in’ forms occurred much more often in men’s speech than in women’s speech. Women tended to say they use the standard -ing forms more often while men tended to say they used the nonstandard -in’ forms more often than they really did.

Since it linked education to upward social mobility, it has become the education system to enable students to function in over one language. This would give students equality of access to educational and job opportunities in the future.

Hence, Malaysian education encourages bilingualism. Therefore, many forms of bilingual education have emerged.