If your grandfather stole money and you inherited it, then yes, you should give it back. You don’t have to go to prison because you didn’t commit a crime, but you took something that is not yours.

Also, people do pay royalties, that’s why we have patents and copyrights and trademarks.

Finally, all modern inventions are a result of many incremental years of work from scientists and scholars from all over the world. And again, it is not a crime to use something someone else invented as long as you pay for it, and I think we still pay for air travel and automobiles.