A leopard can't change its spots
veːelkaː xlupi mɲeɲiː ale povahu ne
In Czech Vlk chlupy mění, ale povahu ne.
This Czech idiom, meaning 'The wolf changes its fur, but not its nature,' conveys the same idea.
Example
"Snažil se změnit, ale vlk chlupy mění, ale povahu ne."
