You should set up profiles to automatically rate models for you. You level up by going through models, but it doesn't do much (slightly increases penis size and adds a new group of models to rate for multiple different aspects, if you'd like.) Monday is when models closest to your desired traits will show up. The "gene pool" just refers to how you've rated the models.
Also, presumably you're not playing the Patreon version which is more up to date with a few new features which include
- A new camera which can generate consent with spot bonuses
- The ability for models to remove clothing gradually to reveal certain parts, which can also be done with your hand tool
- A custom character designer (not complete, you can't change personalities fully)
- Money which can also generate consent if you give it when asked or can pay for sex instead of generating consent.
If I know one thing, the game is better with mods and custom content which only works on the latest Patreon version.