Is it the norm for crystal meth addicts to indulge in bizarre sexual practises?

On "The city addicted to crystal meth",which was a documentary on the BBC,one of the addicts was actually sleeping with his sister!!Does this happen a lot with these people?

: http://alcoholdrugstreatment.info/is-it-the-norm-for-crystal-meth-addicts-to-indulge-in-bizarre-sexual-practises