My kids seem manage Shanghainese, Urdu, English (in RP, cockney and a Pakistani accent) pretty well. I was surprised to hear my son (at the time only four) say

My kids seem manage Shanghainese, Urdu, English (in RP, cockney and a Pakistani accent) pretty well. I was surprised to hear my son (at the time only four) say "Hiro is the hero Big Hero 6." Pronouncing both Hiro and hero correctly.