A leopard cannot change his spots 江山易改，本性難移
米德佳提供中文到英文翻譯服務，含英文編修
A person’s character, especially if it is bad, will not change, even if they pretend it has.
Origin
From the Bible, Jeremiah 13:23 (King James Version):
“Can the Ethiopian change his skin, or the leopard his spots? then may ye also do good, that are accustomed to do evil."
“Can the Ethiopian change his skin, or the leopard his spots? then may ye also do good, that are accustomed to do evil."
