Scientific reason why women are attracted to certain men?

"If you like the smell of a man's sweat, you may be a good match in:
  • Correct Answer: Immune systems
You would probably never think of smelling a guy's sweaty T-shirt to see if he's the one! But researchers gave women this smell test -- and some were turned on by the sweat of men whose immune systems were different from their own.

If you're looking for a mate this makes sense: Children who get several different disease-fighting genes may be less likely to get sick. But it may also affect romance: Women whose immune genes are similar to their partners' may be more likely to be unfaithful."

Could this be a scientific reason why white women are attracted to men who not of their race?