Dr John Bradshaw, PhD, the well-known cat behaviour expert at the University of Bristol, UK, says that with respect to the feline grandparents of domestic cats, most cats will never meet them and therefore they will never remember them. That is a good start!
Dr Bradshaw goes a step further and says that:
“once separated from their mother, kittens seem to lose their memory of her quite quickly, and generally fail to recognise her if reunited”.
If a domestic cat encounters his mother or grandmother later on during his life he may recognise their scents. Although their scent will be familiar but he won’t necessarily regard either of them as family in the way we think of family members. This is referred to as “prior association”.
It is different in feral cat colonies. Bradshaw states that colonies are:
“based around multigenerational cooperation between females — grandmother, her daughters, and their kittens”.
Jill Mateo at the University of Chicago, an expert on “kin recognition” says that domestic and feral cats engage in “phenotype matching”. This is when a cat learns family traits at an early age in their life such as the smell of the cat which allows them to compare cats at a later stage. In this way cats can recognise unfamiliar relatives such as a cousin despite the fact that they did not grow up with them.
Mateo also states that in order to avoid inbreeding within a colony female feral cats can recognise male relatives and avoid them for mating purposes. This is apparently supported by research.
Siblings are often very close for obvious reasons and usually spend more time engaging in social interaction than unrelated cats and their relationship is often characterised by behaviours such as mutual grooming, hunting close to each other and sleeping together.
I don’t know of any books on the subject of cats recognising other family members and relatives, so the pronouncements of Dr Bradshaw PhD are all that I have to go on, on this rarely discussed topic.