 Another case is 'Isabelle', who was incarcerated with her deaf-mute mother until the age of six and a half (pre-pubescent).She also had no language skills, but, unlike Genie, quickly acquired normal language abilities through systematic specialist training.Detractors of the critical period hypothesis point out that in these examples and others like them (see feral children), the child is hardly growing up in a nurturing environment, and that the lack of language acquisition in later life may be due to the results of a generally abusive environment rather than being specifically due to a lack of exposure to language.