Has anyone tried playing this without giving drugs to family members and colleagues I'm just wondering whether taking that option has its own path within the game, and if so how far it's possible to progress when going down that route.
I haven’t done that specifically, but I can tell you there isn’t much difference aside from missing the large majority of the sex scenes. You can date and have sex with Penny without drugging her, but most of her office scenes won’t be available. I onow you can have sex with Diana really early in her route, though I don’t remember if you need to have dosed her at least once. I don’t think any of the other major NPCs have sex scenes without dosing them at least once. Ah, no, there’s also a scene with Lauren if you go out with her on the weekend.
As for the story, you should be able to finish everything that’s been written without dosing any of your family/colleagues without a problem. Except one, of course, but that happens automatically in a story event, it isn’t an option. So it is possible, there just isn’t any reason to do so unless you wanna have a romantic monogamous relationship with Penny. Which doesn’t look any different from drugging her, for what it’s worth.