The risks of allowing cousins to marry are exaggerated in the west and such marriages can even have a positive effect as protection against malaria and leprosy, says Groningen University psychologist Ashley Hoben in her thesis published on Tuesday.

Hoben points out that cousins often married in the past, naming Charles Darwin and Queen Victoria of Britain as examples.
These days there is a greater chance of health problems and birth defects when cousins marry, she says. However, a baby born to a mother who drinks or used drugs has a great chance of health problems.
In 2009, Dutch government ministers said they plan to ban marriage between cousins, which is common in migrant families.