Well, from what folks have told me (Black men and Latinas that date one another), is that they do go with one another because of similar backgrounds...SES speaking, but I DO find it interesting, as some couple friends of mine are from areas of the country that are highly racially homogenous and/or segregated.
For example, a couple friend of mine is composed of a Mexican American woman from Los Angeles and an African American man from Detroit. Both have told me they were raised in low income neighborhoods and that they also were raised in neighborhoods and attended public schools of which their racial/ethnic group was either the majority or the entire make up of the school. Thus, coming to college was their first exposure to mass diversity (my school is located on the 2nd most diverse neighborhood in the nation).
Now there are several ways to look at this:
1) they are going for the first person who is unlike them racially/ethnically because of their past experiences
2) they are embracing the diversity of the neighborhood (reaching I know

) 3) They grew up not wanting to be with someone of their racial/ethnic group
and various more...in the long run, I am hoping that my friends are aware of the consequences and possible reactions of people...some of my other friends really go all out to say "Yeah, we're dating and you can't do anything about it!"....I'm like ok..pass the salt LOL