Genetic relatedness

In a hypothetical experiment, you replace newly born biological child of a couple with another that looks identical. Assuming that the parents have no faintest inkling of this ever, would they be as attached, and consciously or unconsciously as biased towards this child as they would have been with their biological child?

Language

You wake up and find yourself on a remote island that is inhabited by no other human. You have lost memory of all that you have every known or learnt as a social being. Would you be likely to develop a conversational language?

Discourse

You are born into a secluded tribe that is fully blind. Owing to some miraculous gene mutation, you are gifted with an eyesight. How would you rationally convince the tribe that the world is colorful?