He seems to have a lot of interest in other people, and so he tends to stare at them
He's really interested in the people around him, so he tends to stare abit
He seems to have a lot of interest in other people( 彼は 他の人に興味があって), and so he tends to stare at them.( それで彼は ジーと見てしまうのです)
He's really interested in the people around him,( 彼の周りの人に興味があってみたい) so he tends to stare abit ( だから彼は 人をジーと見ちゃうんです)