According to my grandmother (who died in 1979) she was told as a child that our family is descended from a daughter of the 'Duke of Bedford' who lived "over 400 years ago". This ancestor was said to be the source of the "family curse" ... a "mental instability" with associated very high intelligence that resulted in many family members "ending their lives in institutions" (as my grandmother did).
Helen Tudor seems to be a possibility as the family came from a locality close to Bury St Edmunds ... where some sources say she married a local merchant ... and her son, Stephen Gardiner's intellect fits the pattern. My opinion is that this presumably genetically driven trait is a form of Autism (Asperger's?). I think I remember reading a book a while back in which the author (a woman?) claimed that Henry VIII was "schizophrenic". Does anyone know of any studies of the Tudors' that examines their intellect/mental stability?