Gangs.
They were the bane of his mother's existence. He hated gangs because his mother hated them.
Anurak's father joined a gang and started cheating with the leader. When his mother discovered it, she, who was carefree and didn't care for rules and social norms, started hating homosexuals and gangs. On her deathbed, even though Anurak was young and wasn't really clear about the things happening, she made him promise never to join a gang and stay away from homosexuals.
The more Anurak grew into his own man, the more he saw how unreasonable some of his mother's teachings were. Especially when it comes to getting close to homosexuals. They are humans after all, and it is wrong to blame all of them for something his father did.
Not just that, he could be one too because he knew he liked men. How did that make him a bad person?