Context: someone said a bunch of stuff that Haruhi ハルヒ never heard about.
{Tamaki-senpai ga haafu to iu} no mo {kiita} koto arimasen shi... 環先輩がハーフというのも聞いた事ありませんし・・・
That {Tamaki-senpai is a "half,"} too, [I've] never {heard about}.
[I've] never {heard about} {Tamaki-senpai being half-Japanese}, either.
tashika ni kami toka chairoi kedo tabun puuru no hairi-sugi de 確かに髪とか茶色いけどたぶんプールの入りすぎで
It's true [his] hair and [so on] is brown but [it's] probably because [he spent too long inside the pool].
Top signs a character doesn't have two Japanese parents:
His hair is not black.
His eyes aren't black, either.
puuru ni hairi-sugiru プールに入りすぎる
To enter the pool too much.
To spend too long inside the pool.