It makes it harder to speak with women ("nerd" might have the same feature) you need to be drunk or have high charm otherwise the MC will clam up out of nervousness. Also, I'm pretty sure it starts you off with smaller genitals which also affects relationships with the women.I get there is no femdom since there is no tag for it, but what does "loser" background for? Is it just to be more challenging and that's it? It doesn't go for any unique or specialized content?
I believe the end goal is to provide flavor text and game changes for all backgrounds.