How to randomize sexuality?

[kreaturen]

I'm trying to develop a population's preferences and, are able to do it... It's just that unless they already are in a relationship, they always end up bisexual. The ones who are in a relationship become 100% into that sex. I vaguely remember that I was able to generate a population of more varied sexuality before, I just can't figure it out now. Preferably, I would like 85% of them straight, 10% gay and 5% bi. 

 

I've re-read the tutorial on attractiveness, but didn't really find the answer I'm looking for. Does anyone have any tips?

Also, how does the WW likes and dislikes in CAS fit into all this?!