Romney certainly made mistakes in high school - as we all did. But the upside of mistakes is that it is sometimes the best way to learn. Look at Barack Obama. He did cocaine in his younger days and came out to say that it was one of the greatest moral failures in his life. It was a mistake that he made, has been able to recognize and move on from.
So it is with Romney. He made a mistake and he owned up to it—wait, what? He claimed to not remember it and offered a conditional apology? So he didn't actually apologize for the incident, but for all of his "hijinks" and only if he "hurt anyone by virtue of that"? That doesn't really sound like an apology.
That's okay though, because even if Romney picked on people he thought might be gay, at least he fights for equal rights for all Americans - gay or straight - today. What? He doesn't? He wants gay couples to not enjoy the same rights to marriage as straight couples? And tries to justify it by using history, claiming that his homophobic religion has nothing to do with his decision? That doesn't sound very believable.
So even from all of the talk of how prestigious Cranbrook is and how hard he studied, it seems as if Mitt Romney learned little from his time there.