my ex was adopted but in his adoptive family his grandparents were first cousins and thank god he was adopted, as they were really an advert as to why cousins shouldnt marry. There was something dramatically wrong with all the boys they had and it has extended into the grandchildren. Both sons had polycystic kidneys, brain tumours, various cancers and breathing problems, one son died in his 20s the other at 50 ish. One grandchild had childhood leukaemia (sp) and severe autism, another died of of some sort of brain tumour, another is an hermaphrodite and one has asthma so bad that he was in hospital most of his childhood.
You cant help who you fall for I suppose, personally it would never happen to me as my cousins are like brothers and sisters to me. I think its very important you dont have children with a family member, the law is there for a very good reason. You only have to come down here and have a look round Bridgwater to see that ( and that is not a mean joke either)