I am reading a book: "Bridget Jones: Mad about the boy" but I have found an expression which I don't understand: "to have older brothers". This is the sentence:
"Did she hurt her mouth?" said Billy, looking puzzled, at which Jeremiah, who had older brothers, spurted out laughing.
This is the context: Bridget was in the bushes with Mr Wallaker who try to kiss her but her son and his two friends surprised them. I don't understand the expression "older brothers" I don't think it refers to the fact that Jeremiah actually has older brothers. Thank you very much in advance for your help