I don't know, but I cannot remember Hurley ever speaking in Spanish, not even to his mother, or father, etc. Not a single moment, I mean, we've had Korean, Arabic, German, French, Thai, and lot more ... but not single time I remember Hugo ever speaking a single word of Spanish, in fact i remember Sawyer calling him "Issi" several times.
Why is this an issue? well if Spanish wasn't his mother tongue, or if his family nurtured English more than Spanish, then he might end up not a natural born child to the Reyeses, which works perfectly well with the fact that he is Special.
But this will lead to the next question, who are his real parents?