I'm looking for a name of a cognitive bias that describes the following phenomenon:
A person has been exposed to some area of expertise from a very early age (think 7-10), and for an extended period of time. This can be sports, computers, musical instruments, etc. As the child matures, the child does not realize that such exposure has created a level of competency where even advanced tasks are easy for them.
After growing up such child may be surprised to find out that ordinary people do not have his/her level of expertise. As adults, such people can continue to write books or give advice, being [completely] oblivious that others do not come even close to their level of expertise.
What is the name of this cognitive bias, where individuals do not realize that other people do not share the same level of expertise?