Salams everyone

Firstly, I am kind of new here, so be nice please! Anyway, my reason for posting is that I have a bit of a problem. I have a brother who has not embraced Islam properly.

Although he acts Muslim, reads namaaz, and reads Qur'an when told to, he only does these things because of our parents and, when out of their view, changes his behaviour and attitude completely. Lately he is becoming worse and worse, swearing repeatedly, arguing with my mother and myself for the sake of it, lying constantly, and going against the ways of Qur'an and Hadith.