I don't see a problem with incest if both parties are consenting. Having a child through a relative is more likely to cause genetic defects though, so unless the potential parents are willing to deal with those risks I don't believe they should have children.
"God is dead" - Friedrich Nietzsche
"Faith is what you have in things that DON'T exist. - Homer J. Simpson
"Faith is what you have in things that DON'T exist. - Homer J. Simpson