I've just been reading Hans Günther's book "rassenkundes" chapter about the denordization of Romance Europe. He was so eager to show that most influent italians where of nordic blood that we relied on inaccurate portraits and he scarcely verified his sources; let's disecate some of Günther's fallacies:
About Leonardo Da Vinci
the portrait usually displayed to ilustrate Leonardo Da Vinci's Face:

Is labelled by most historians and biographers as being a "presumed portrait of Leonardo" I asked to german historian Maike Vogt Lüerssen -personnal friend since a yer ago- and complete stranger to this "racial make-up" stuff if it was really a portrait of Leonardo Da Vinci her reply was "that's a good question; people usually thinks yes but is not so sure; at beast it could be a XVIIth century depiction based on a drawing now lost and supposed to be a self portrait of Leonardo".Most Leonardo's biographers say that his contemporaries mentioned his beauty but gave no indication about his pigmentation. Moreover, Vogt-LÜrssen has discovered at Washington Gallery a Leonardo Da Vinci new self-portrait in which he does not look nordic at all :
Leonardo da Vinci
Raphael Sanzio (1483-1521)
Günther displays this image copy from a "portrait" by Bindo Altovitti, probably idealized according to renaissance ideals and dating of 1518 :

He treachously relyed on portrait above instead of relying on Raphael's own SELF PORTRAIT BELLOW:
Galileo Galilei
He ascribes him nordic features according to this portrait

not only that Galileo shows a quite unnordic nose here but also he relyes on a portrait that he does not even now how accurate is. Contemporary portraits show him rather of cro-magnonid type:
Macchiaveli; Günther ascribes him blue eyes; on which basis???