I took a Latin American history class in college. Basically, the Spanish had a different approach to colonialism and miscegenation than the English. Most Spaniards in the New World were conquistadors, who were all men, and when they came they had no qualms having children with the native women. They were primarily utilizing the Americas for its resources and to spread christianity; with so many mestizo children being born to the conquistadors they eventually had to include them in the social hierarchy and give them societal privileges that were just below pure-blooded spaniards (called penisulares) and almost comparable to the criollos (pure blooded spaniards born in the Americas). However North America was colonized by the English as a settler colony, where actual families and communities were being shipped over. These groups were much more conservative and were more interested in expanding their own communities they brought with them rather than mix into the native population. I mean both colonial powers were super racist and horrific, but the Spanish/Portuguese had less qualms about race mixing and marrying into different races. Funny enough, it was illegal at one time in Paraguay to marry someone of the same race as yourself.