It was hard work for a mother to bring up healthy children in the 30s in Glasgow - the environment was kill or cure.
Balini's mother kept the home scrupulously clean (and scrubbed the children, too, I daresay, if she was anything like my grandmother in a different city) - so no E coli indoors. She spread butter jam etc with the same knife (nothing much wrong with that, it was all going onto the same slice of bread and being eaten at once) - but I don't suppose she licked the knife in between, or used it to scrape the mud off shoes before spreading. My grandmother would have skelped the ear of anyone who did that, or ate with dirty hands!
We live longer these days, with that comes the increased likelihood of lowered immunity - and there is more awareness of bugs and germs. Infant and child mortality has been dropping in the last century, but the after-effects of even mild infections are still causing illness in some older people.