Would a parent's citizenship affect a UK visa application for their children? [closed]

My sister will travel to the UK using her British passport; she is visiting our mother for two weeks. She would like to travel to the UK with her two children, 3 and 9 years old; both are Iraqi citizens who do not have British passports and have never been to the UK. She will apply on her children's behalf; in other words, she will fill the visa application for them.

Does her nationality have any positive or negative impact on the application?

Note that my sister was born outside the UK and never lived in the UK for 3 consecutive years before the oldest child was born.