Westermarck, History of Marriage, Chapters XIV and XV.
Crawley (The Mystic Rose, p. 446) has pointed out that it is not legitimate to assume the possibility of an "instinct" of this character; instinct has "nothing in its character but a response of function to environment."
Fromentin, in his largely autobiographic novel Dominique, makes Olivier say: "Julie is my cousin, which is perhaps a reason why she should please me less than anyone else. I have always known her. We have, as it were, slept in the same cradle. There may be people who would be attracted by this almost fraternal relationship. To me the very idea of marrying someone whom I knew as a baby is as absurd as that of coupling two dolls."