The writings of Scottish deputy commissioner for lunacy Arthur Mitchell claiming that cousin marriage had injurious effects on offspring were largely contradicted by researchers such as Alan Huth and George Darwin.
In fact, Mitchell's own data did not support his hypotheses and he later speculated that the dangers of consanguinity might be partly overcome by proper living.
Anthropologist Jack Goody said that cousin marriage was a typical pattern in Rome, based on the marriage of four children of Emperor Constantine to their first cousins and on writings by Plutarch and Livy indicating the proscription of cousin marriage in the early Republic.
Professors Brent Shaw and Richard Saller, however, counter in their more comprehensive treatment that cousin marriages were never habitual or preferred in the western empire: for example, in one set of six stemmata (genealogies) of Roman aristocrats in the two centuries after Octavian, out of 33 marriages, none was between first or second cousins.
In the past, cousin marriage was practised within indigenous cultures in Australia, North America, South America, and Polynesia.