Well obviously, the entire human race is sexually compatible between opposite sexes, so that's something biologically that can be said, possibly in favor of interrracial marriages.
There might be cultural or religious questions, about marrying "outside the group," and thus corrupting culture, but if people be of the same religion, and of similar or compatible culture, I don't see any problem with it. I would want for people to be with their proper soulmate, and to have lots of babies, to add all the more people to the world to also enjoy life.
To say that people can only marry within their race, couldn't that sound a bit too much like Nazi-like eugenics theories? Humans are of one race, not like mere animals where we can distinguish between "purebreds" and "mutts." Maybe there's a difference with mere animals, but humans should be so much beyond that, that there could be little difference with us.
In fact, I am white, and one of my best friends, that I trusted for advise on who I should vote for, was a black conservative pro-lifer, married to some white woman, a preacher and father of several children. He was about the only black guy that showed up at our abortion clinic pickets, drawing volunteers who felt called from many Churches, and he was a Republican I think. Talk about "stirring the pot?" I talk in past tense, because I have since moved to another locale.