The thing about this is we have to remember is that people have justified these kinds of rules for thousands of years for reasons we now find silly, but seemed carved in stone to them at the time. In Russian Monarchy you still can't be considered a direct line descendant who can inherit if even one of your ancestors was not Russian Orthodox and married without dispensation from the Czar. A little over one hundred years ago you could not legally marry a Native American. In Nazi Germany a German could not marry a Jew and previous such marriages were considered void. In the United States, a "white" could not marry a "black" (definition varying by state) in many states until the 1960's. At different times aristocracy could not marry commoners and in fact this is still talked about. This issue has happened with "heretics" and Catholics, Protestant and Catholics, and Muslims and Christians. It's even going on now with Sunni and Shiite Muslims.
At the time, all these distinctions seem inflexible and all of them were said to be divinely ordained. In retrospect, we reject almost all of them out of hand as ludicrous. Sometimes you stand too close to the painting to actually see it the way the artist intended. That's probably why the bible says Judge not, let ye be judged. So, to me, if you want to marry your dog and leave it all your money, I don't care. If God, in whatever form, has an issue with it, he or she can take it up with you. That's not my job and I believe it's called free will for a reason. We all have free will to make our decisions and it's up to divinity in whatever form to take it up with us if we are wrong.