If you don't change anything then your sims should behave just as they did before, as far as I understand "experimenting with both genders" was the default setting before which have allowed players to do what they wanted.
From what I could see all my sims had this setting as default after the patch and I don't think you can change it through gameplay? I think that's something that you do in CAS. I spent some time to change that for some sims that I felt that they would not want to explore romantically, like my married sims.
What might have changed are your sims gender preferences as it looks like they will change depending on how you have played your sims, many of my sims had gender preferences already selected.
I have not noticed any new actions or consequences, my sims seems to behave as I have always played them and I have not noticed anything different for the other life stages.
