I got my answer from the video you linked to here, to this question that I posted before: --------- I was wondering: If 2 newborn babies exchange families from the hospital immediately, one purely Chinese and one purely American, do they learn the language slightly slower than people who are born to families that purely from old generations speak the same language as the baby as supposedly the DNA has some prepositions to the language and its tones and its grammar? ----------- but I'm still skeptical.