Why is my 1-year-old female cat licking my 1-month-old female cats genitals?

Question
I have a female cat for 10 months now, she will be 1 year old in a couple of days. About a month ago, i found a newborn female kitten on a pavement in a really bad shape. I took it to the doctor, looked after it and brought it home. At first, the big cat didn't want it around but now they are constantly playing together.
Recently, i noticed that the big cat is licking the small cat's genitals. She doesn't lick her anywhere else and the small cat doesn't seem to bother. The big cat is not neutered.
I was wondering if there is a sexuality issue going on i should be aware of.

Answer
Beth,

Your big cat is cleaning the little kitten like it was her own and being maternal, not sexual. To be a sexual behavior there has to be a 'smell' and the kitten is too young for that.

The kitten likes it because it comforting being cared for like it's own mother would do. You are lucky that the older cat accepts the kitten, a lot of them don't. It will make the kitten more well-adjusted.

Your cat may be pregnant which would also make her act maternal. You may want to think about getting her spayed soon.

If the kitten is not screaming and trying to get away then I would not worry and let 'foster mama' do what comes naturally to her.

Tabbi