Like I mentioned before, there are numerous spectrums of sexual attraction, some naturally occurring with no outside influence, and some are the result of conditioning.
In some cases, heterosexual relationships can be the result of a certain level of conditioning. For instance (and this scenario isn't all that uncommon for many gay men), there are many gay men who will date, marry, and procreate with women (even though that's not their first choice) to conform to what their families and society view as "normal", and then they'll come out years later after all of that.
...and even what societies have viewed as normal has shifted and changed over time. It was fairly commonplace in pre-conquest Americas, and are on the earliest recorded history from East Asia. The same is true of the Middle East from the 1500's to the 1700's...same goes for Europe.
However, many modern day folks seem to think that westernized, predominately Christian, nations (circa 1700-2017) have the monopoly on defining "Normal" for the entirety of human history.
Naturally occurring ones, for instance (and I'll use myself as an example), would be like my preference for Asian women vs. White/Black/Hispanic/etc... It's not something I can change or make go away, it's just the way it is.
The fact only 7% of relationships are interracial would be a strong indicator that there is some conditioning still happening at the racial level too and that the "you have to stick with your own kind" mentality is still at play to a degree.