In order to persuade Mira to tell you her secret you'll need a Persuasion of 9. Tell her that you've hit a jogger with your car once and she'll confide in you. If you tell her about Adam and Chris you'll also get $100 for each one.
With a Persuasion of 8 you can make Adam tell you his secret. Just ask him why he is so desperate to find an investor. If you tell him about Mira and Adam he'll give you a Gold Ring and a Fancy Watch.
You'll need a Persuasion of 9 to make Chris talk about his secret. Tell him that you're an atheist and he'll confide in you. You get nothing extra from him if you betray the others to him.
If a non-combat approach is taken to entering the Mansion it is possible to speak to Mira Giovanni, Christopher Giovanni and Adam Dunsirn to discover their secrets and report them to each other for rewards. With the Unofficial Plus Patch this will be listed in the quest log as Dirty Dishes.
This is only possible at the Giovanni mansion. Tonight is the night that the Giovanni will choose one of their family to "embrace" into the inner circle. There are three main contesters that you'll meet, Mira, Chris, and Adam. Each one of them has a dirty secret and they'll all ask you to dig up dirt on the others for them, in order to gain the advantage in the contest. You can give away each secret ( 1 EXP) until one of them has gotten two ( 1 EXP).