Then you're still left with the same problems:
1) Would you marry a brother and sister if one of the couple was sterile and couldn't have children (or they just didn't want to have children)? What if they want to adopt a child?
2) Using this logic, how can you permit people with genetic problems to marry, considering the fact that they have an exponentially higher rate of birth defects or hereditary problems?
3) If it's "moral issues", then you may be justifying the opinion that some people hold. For instance, how is the statement "It's immoral for brother and sister to marry" any more valid than "It's immoral for two men to marry"? What makes one statement true and not the other?
If you're going to bring human rights into it, then an oincestuous relation has the human right to marry as well, seeing as how the Declaration doesn't provide any specifics about such matters. (Actually, it says that the State should protect marriage and the family, but then you get into interpretation etc.)
let us review your reasoning...
#1 your saying and #2 that what about a Sterile Brother marrying his Sister and then why Marry with Hereditary problems etc.
First of all Marrying anyone but the opposite Sex is an Abomination unto God. Brothers marrying Sisters is simply Incest, and another Abomination unto God. If we Marry someone with Genetic defects, how many people who know othis about the other before they Marry? You using Hypothetical in both cases.
Can you see the following situation whereby a couple is discussing their future together prior to Marriage
, and the Future Bride tells her future Husband.;
"Billy, I need to tell you something; about my Family. We have a History of Genetic problems, and it involves the 4th Generation in our Family, with the Female side. Every Fourth Generation, One of The Females gives Birth to a Frog-like Male.
This started about 200 years ago, and This Man creature is half-human and Half Frog. There is a GENETIC problem involving this so please be forewarned before we Marry. I am the Fourth Generation since the last time this happened.
So we must be honest with ourselves, and I do not want you to Unaware of this.....ribbit.....ribbit..
UNow how many Brothers and Sisters do you think Actually Marry, compared to Lesbians and Gay Guys who either Marry or want to Marry? This is like comparing Apples and Oranges.
Here is scripture to back up what God says about Homosexuals OR Inter marriAge between Close Family Members.
Leviticus 18 v 22-23 "Thou shalt not lie with MANKIND as with WOMANKIND; it is ABOMINATION."
Verse 23; Neither shalt thou lie with ANY BEAST to defile thyself therewith; Neither shall any Woman stand before a beast to lie down thereto: it is confusion"
Leviticus 18 verses 1-21 deals with Having Carnal relationship with any immediate family...please read it all.