Medically.....NO.
In regards to the morality.....well......that would depend on YOUR belief system and no one else's.
There have been famous people in history who have even married their distant cousins, i.e. American president FDR.. Franklin Delano Roosevelt.
family is not suppose to have sex with family. It is very immoral. If you think it is okay, you and your cousin should come out the closet and tell your family. See how they react to it.