Registering without required fields

[symptome]

I've got the gender-hack installed. So, during registration, the user will be ask about his gender. This is a required profile field.
BUT:
I don't want required profile fields to show up in registration.
The registration process shall be lean. Just entering user-name, password and email adress and that's it.

The user will be asked for the required profile fields, if he first logs in. And that would be great.
But I don't get it, that the required profile fields don't show up in registration.

Any tips on that?
Thanks a lot!

Marcel