Yes, unfortunately they can be!
We had a dreadful experience a few years back. My daughter bought a baby female Syrian from a reputable pet shop. Back it came, all cosy home alone in lovely housing ...... until lo and behold, she was not home alone any more!! She had 6-8 babies!!!!!
And yes, she killed and ate every one of them. One minute they were there, the next gone but for a few remains!! It truly was a hammy house of horrors!!!
We sought advice and were told that the original hammy was too immature to cope with the babies. guess a cheeky chappy hammy had been sexed wrongly at the pet shop and had made the most!!!
However, on a lighter note, original hammy lived to a ripe old age - on a diet of seeds, nuts and fruit etc. Def no meat on the menu!!!!