[cypher]

Which species of hamster do you have & how long have you had them?
Are they biting in or out of the cage or both?
Some hams can be a bit territorial about their cages & do better with handling & interacting out of the cage in a safe play area & are less likely to bite.
Always start by offering treats from your fingers so they can just take it from you, when offering food on your hand it can help to bury your fingers in the substrate at first so they aren't on offer for biting!
A lot of hams can take some time to figure out where food/treats end & hands begin so often bite a little or nibble but soon get over it.