Apparently the best selling books on Amazon are thrillers and romance. Not exactly a surprise I guess. I was discussing this with a writer friend, and we thought we should combine these into another genre - crick-lit.
This article talks about a romance formula and scientific options for finding the right person for you. It looks at smell tests, DNA analysis to assess compatibility, and facial analysis. Interesting article, but I'm not sure it would make a good romance novel.