Your Mam being unable to control her temper, by the sounds of it.
I think some people here are equating a spanking (which I would consider basically a light slap on the arse) with a savage beating.
Indeed. Losing one's temper can hardly give any good results, no matter the circumstances.
Children are curious. Probably every child will, at one point, try to find out "what happens if I intentionally misbehave and defy my parents?". At this point, a slap or two is very much called for. Most important thing a parent must ensure is that their children have a good reason to love them. Giving them a good reason to feel respect as well is the second most important thing.
Child psychologists also say that children need well-defined and enforced limits to feel secure and cared for.