[hm. if this other guy knew what Quirks were, then he probably would not have needed to ask. in that case, Shouto will explain to Rin more thoroughly]

...Back on my world, some people are born with powers, like these. We call them Quirks, and a lot of people want to try using their Quirks to become heroes... or villains. It is possible for Quirks to be passed down, so... [his eyes narrow] My father arranged for a Quirk Marriage, because he wanted stronger children. [for reasons] I got my fire powers from my father, and my ice powers from my mother.