What was the first thing that cast doubt on the authenticity of the king being peter wilks's english brother?

Their faulty English accent was the first sign of doubt about the two conmen.  Doctor Robinson pointed out that their English accent was terrible.  When the two conmen decided to suddenly sell all of Peter Wilkes’ possession right after his funeral.  Wilkes’ daughters as well the whole tow were against this and it aroused more suspicion but the two conmen proceed to do so prompting Huck to tell one of the girls the truth about two men and the money. Hope this helps!!!