We have to look at the history of the word ‘brat’.
Brat is an English word that we use for badly behaved kids. However, it originally came from the 1500s when it was used to describe beggar children who wore a ‘bratt’ – a word in Old-English for a type of cloak.
This word actually came from the Irish language, and is still used today. It can mean ‘cloak’ and is the root of the word for ‘flag’.