Advocates of cousin marriage say they're against sex between siblings, but they can't explain why.
Cousincouples.com, the Web site to which the NSGC study refers couples for support services, wants to keep Big Brother out of the bedroom.
Science has deflated the scientific objections to cousin marriages. North Carolina and West Virginia explicitly prohibit me from marrying you, but 20 other states don't. Because if it is, bear in mind that you and I have as many genes in common as an uncle and niece do.
If you and I can marry, why can't an uncle and an adult niece? Would you rather restrict marriage to ordinary first cousins? First cousins have as many genes in common as a man and his half-brother's child do. If first cousins can marry, why can't Roger and Chelsea? If you still won't cry uncle, let's look at hard-core incest.
Many cousin couples can't pass on genetic diseases, since they're infertile. If not, maybe the 24 states that ban cousin marriage should follow the lead of the five states that allow it if either party is sterile. If your purpose is to prevent people with dangerous genes from marrying each other, why use a crude standard such as kinship?