1-3 : I have no problem with, if there is consent and understanding from every party !
4 : cousin marrying is autorized in some country, the only bad thing its have baby.... but after all their choice and won't care much. (and from bible we all kid from adam & eve so.... :p)
5 : Will never happenend, kid can't choice !
And for finish, if ppl would stop look at other and make their own buisness, t here would be a lot less war and more peace...