Responses
But he does indeed have a type tho. It was established right from the very first chapter.
It was established but not specified. Hence, his "type" doesnt necessarily equate to pink hair. And dwelling on his backstory, it was neither implied nor explicitly shown that he has a romantic admiration towards his tutor (leaning more on caring for a sister) — a solid presumption that pinkness of hair doesnt have any to do with his "type"
The pink hair semblance is not cause they're "half-siblings" or our seme has a "type". It's simply the author's way of showing that the characters are damn pretty gorgeous and different (everyone else in the story has brown or black hair). Pink hair could also make these characters stand out (at least in the story)