Your parents did more than many farm people would. They fixed the cats, and provided shelter and food. Cats that are born and raised on farm are working cats - if they had a mother who was a competent mouser who taught them how to hunt. There are fewer resources in rural communities for low cost spay and neuter. Those farm cats sound like they had a good quality of life.
I grew up in a rural community and am aware of some of the practical but heartless solutions many farmers use to deal with excess litters of kittens and cats(ie drowning, shooting, poisoning).
