hmmm, something wrong with young Ben, yes, two words: his father. Trust me Benmer, I was suprised they made him out to be a sympathetic figure at the beginning of his ep, which changed rapidly during the events, but I can see why he was quiet as a child.
Most likely, his father would get drunk and berate little 'henry' about things the boy had said and done, since Uncle rico obviously loathed the boy, so better to be quiet. Also, living in the dichotomy under the guise of an island research facility looking for peace and harmony while you live in fear and anger with a drunken father, well, thatwill probably shake loose some marbles.