[yummyfajitas]

What I meant is that it's immoral to make decisions based on ideas you have of people that have not been proven.

In that case, it sounds like most startup founders are immoral by your definition. The vast majority of startups make decisions based on ideas they have about people which are not proven, i.e. "people would like to rent out their home to strangers".

...but if you do it by thinking that those things are natural to the gender, the become immoral.

What if you don't know whether those things are natural to the gender or learned, but make decisions based solely on predicted (or demonstrated) consumer behavior? I.e., "these pink cars sell really well, mostly to girls, I have no idea why. Lets make more and market them widely."

Or what if you are just testing hypothesis? "Lets try out pink cars, aliens, babies, pirates and zombies, and then see what sells." Would that be immoral? It certainly lacks the certainty you seem to want, but it is how many businesses make decisions.

[lomegor]

Yeah, you are right on that ideas making an action immoral do not make too much sense. What I'm trying to say that the idea behind those actions is immoral, making the action immoral. But still, I'm not sure about that.

I am sure about your second part. If you make decisions on predicted consumer behaviour, most of the time you are OK. The same happens when you are testing an hypothesis or something like that. What makes it immoral is propagating the stereotypes and probably worsening discrimination. So, it isn't a problem if you assume all men want to clean their hair or don't want to have dandruff. It's not OK if you assume all men don't know how to cook, even if it has been predicted (or demonstrated) by consumer behaviour.

It's not that these actions are always bad, is that they are bad in the current society we live in.