Just playing Devil's Advocate here what the article actually says mon frere is, 'The risk of giving birth to babies with genetic defects as a result of marriages between first cousins is no greater than that run by women over 40 who become pregnant' That is a very different statement than saying all first cousin marriages at all ages are sound. The actual risks to both mother & child if conceived after 40 are actually quite high. The article also states, 'the risk of congenital defects is about 2 per cent higher than average for babies born to first-cousin marriages – with the infant mortality about 4.4 per cent higher – which is on a par with the risk to babies born to women over 40. "Women over the age of 40 have a similar risk of having children with birth defects and no one is suggesting they should be prevented from reproducing," So there is a higher risk factor. Now if people wish to still marry first cousins, knowing this then fair play. However to infer & suggest from this article that all first cousin marriages at all ages are the same as non cousin marraiges in terms of potential risk is not true & misleading-if we use this cited article as a base. If you said that such a union is not prohibited by God or God's Messenger & they know best it would be a different argument.
:s1: http://www.independent.co.uk/news/science/theres-nothing-wrong-with-cousins-getting-married-scientists-say-1210072.html