Yes, types are in-born and hereditary. But like I say, if duality is in the family, then that’s familiarity for people to recognize their duals. Duality irl is better suited to friendship, or business because it’s a relation of relaxation. Supervision is the most common for marriages. My dad is LSI but from what my mom described about her dad, he was likely LSI, too. My mom’s dad is LSI, and then she married my dad who’s LSI. My dad is LSI, and 3/4 relationships I’ve had is with LSIs.
Consciously, we don’t go looking for specific types, but unconsciously we’re wired to find what we’re most familiar to.