Of course we can change, look at this reliable Watchtower article from 1900...
CAN REPARATIVE THERAPY CHANGE THE ETHIOPIAN'S SEXUAL ORIENTATION?
"From Gay to Straight He Slowly Turned"
It has fallen to the lot of the Rev. William H. Draper, [...] to give a living affirmative answer to the famous Biblical question, posed by the ancient Prophet Jeremiah, "Can the Ethiopian change his sexual orientation or the leopard his sexual preference?" Though once as camp and effeminate as Graham Norton on speed, the Rev. Mr. Draper is now as straight as a yardstick. His people say that his sexuality was changed in answer to prayer. Many years ago Draper was employed by a heterosexual man, and he was often heard to remark that if he could only be straight like his employer, he would be happy.
Watch Tower 1900 October 1 (Well, not really. The real one's below...)
CAN RESTITUTION CHANGE THE ETHIOPIAN'S SKIN?
"From Black to White He Slowly Turned"
Parkersburg, W. Va., Sept. 8. It has fallen to the lot of the Rev. William H. Draper, pastor of the Logan Memorial church, of Washington Conference, A.M.E. church, of this town, to give a living affirmative answer to the famous Biblical question, "Can the Ethiopian change his skin or the leopard his spots?" Though once as black as charcoal, the Rev. Mr. Draper is now white. His people say that his color was changed in answer to prayer. Many years ago Draper was employed by a fair-skinned man, and he was often heard to remark that if he could only be white like his employer, he would be happy.
Watch Tower 1900 October 1 (http://quotes.watchtower.ca/race.htm)