For a summary of the evidence on this point see Havelock Ellis, Man and Woman, fourth edition, 1904, pp. 256-264.
"The Comparative Abilities of the Fair and the Dark," Monthly Review, August, 1901.
The fact that even in Europe the abhorrence to incest is not always strongly felt is brought out by Bloch, Beiträge zur Ætiologie der Psychopathia Sexualis, Teil II, pp. 263 et seq.