How can my sims get a reputation?

Hi i have all the sims 3 games like the expansion packs i brought generations and you have the scrapbook and i playing a family and saw the scrapbook and it had how many relationships he had/has and then it had like a red thing underneath and the reputation said 'naughty' but on his sister page its got reputation 'none' how do i get a good reputation? what do i need to do?