There are as many different types of Sephardim as there are Ashkenazi. And there are many other factors, such as where did the boy learn. We know quite a few boys like that, in fact, except for their nusach, you probably wouldn’t know they’re Sephardi, which includes their physical appearance, ie, not all Sephardi are dark haired.
Maybe 20-30 years ago, it was also considered “intermarriage” when Litvaks married Chassidim. Now that’s quite common too.