the chance of a hamster from a good source having an illness that a human could catch is very low. Yes, there are diseases that rodents can spread to humans like Hanta Virus, etc., but the chances of a domestic animal from a good source having one is rare. there are a few parasites like a species pf tapeworm that can be found in hamsters and that can be transmittied to humans (only if the animal is infected) but proper cleanliness and handwashing after each handling of the animal (and this is a good idea regardless of the pet) will greatly prevent this. As long as the animals have not been taken out of the wild (and yes, there are colonies of feral hamsters and gerbils in California due to people releasing pets and the pets being able to adapt and survive and the climate in Southern California is similar to the wild hamsters habitat), and are from a good source, most experts agree that the risks of contracting something from an exotic pet are very low. (and this came fromtexan A&M University School of Vet Med: Dr. James Johnson, "Contracting Diseases From Exotic Pets Not Likely, Expert Says" But talk to your father. There may be other reasons why he does not want you to have a hampster right now and he is using the health as an excuse. he may not be sure if you are ready for one or may be worried that you will lose interest in a few months and someone else will end up caring for it. What if the family goes on vacation or if you decide to go to an overnight camp of a week or two – who takes care of the pet?