Oh! my hamsters were definatly not torn away from their mother. I picked them out before they had fur somehow the breeder either remembered them or just picked two babies and said they were them when I got them. Either way I got them later when they had fur. Even the two had different temperaments and personalities, Charcoal was more docile and a bit lazier where Moriarty was more apprehensive and energetic. Sadly when Moriarty died charcoal got more inactive so I think he may have missed living with his brother. They're both gone now... anyways I'm pretty sure they were pure-breeds.

Yeah, some hamsters generally have different temperments, although you had them from the start -- when they were only furless babies, which gave them a better start to having bonded with you.

Did your brother breed the mother hamster, or did he buy them both from birth? If they were bought when they were furless and therefore seperated from the mother, it can stress hamsters out or means they didn't have a very careful seller. Babies should only be seperated from the mother at four - five weeks, which means by then, they would've grown fur.
If not, though, it's possible your roborovski's might've been hybrids, which might've temporerily stunted their fur growth. I don't know the details, but it sounded like your hamsters were a pretty fun pair. I've been caring for hamsters for some years now and they never get boring.

It's odd my 2 roborovski hamsters were extremely friendly and playful from the start. I guess I was just lucky. They were brothers and I picked them out before they even had fur. Charcoal and Moriarty