In any case that's not Snake's issue since he -is- attracted to people from him country, isn't he? His straight crushes and all?
I just think we can have preferences, even if they're strong, and I don't think culture puts them there. Gender roles are cultural - you literally get told "don't cry! boys don't cry!". No one EVER tells you "feet are attractive, guys with glasses are cute, dark hair is pretty!". In the cases of fetishes BTW I'm not finding any support for the theory that they're cultural. It makes sense because people tend to have similar or downright the same fetishes all over the world in all cultures.
Let's put it this way, if we make the highly unethical experiment of isolating a child from
any human contact whatsoever, would he or she really have sexual tastes, or even a sexual orientation?
We can't really separate culture and sexuality because sexuality is intrinsically a social experience, the culture of a society plays a big role in how people relate to each other. We only need to see how fetishes and sexual desirable traits change over time. Take glasses for starters, when they were first invented they were considered awful and incredibly embarrassing to wear, a sign of someone unhealthy and awkward, with time they gain acceptance and popularity and now they are not only fashionable, but sexy! I do understand there are some basic primitive instincts that society can do little to change (and sexual orientation might be in that group), but things like "curly hair is sexy!" is a complete fabrication of the society you grew up in. You found it appealing because society showed it to you that way.
And I disagree people tend to have similar (much less the same) fetishes in all cultures. Thanks to globalization what is consider sexy has started to be more homogeneous indeed, but even then if you look closely there are stark differences, take Japan's fetishism of innocence, cuteness and childish behaviors for example. Over there a woman to be appealing does all those things that make her look more innocent and child-like. However in the west that would be considered awkward and undesirable, because it shows immaturity.
Edit: Or let's take your native Mexico, or Latinamerica for that matter, the preference for Caucasian race is not a coincidence or random event
at all, it stems from colonial times and the complete dominance of European races as well as the segregation of native and black slaves, we are bombarded constantly by these prototypes of beauty in all media in existence, magazines, TV, films, etc, etc, etc.