Does a Pokémon's gender when breeding with Ditto affect the offsprings' gender?

My sister has been breeding a bunch of Popplio because I want to FINALLY have a female. She started with breeding my male Primarina and a Ditto I traded her. After hatching around 20 eggs, she finally got a girl and put it with the Ditto instead of my male Primarina. Now, she's gotten 5 females out of 8 eggs.

So my question is: if being bred with another female Pokémon, do Ditto and that Pokémon have a higher chance of getting female offspring? Or is it just luck? I'll be trying this method with other Pokémon.

Each Pokémon has its own gender ratio, which is not affected by who its parents are- or in fact anything at all. In Popplio's case, the male:female ratio is 7:1. In short, your sister simply got lucky.