Am I allowed to have adult content on my forum. Like I can have a adult section and in there I won't have my google ads but every where else where is no adult content I will have google ads is that allowe?
Technically the Policies say that SITES which have adult content may not have adsense ads. To me, that would mean the answer to your question is NO. However, I have heard of cases where people have contacted Google with the question and they were allowed to still display ads on the non-adult/mature content pages. I would NOT put adsense on this site without contacting Google first and getting their blessing.
According to their policies I'd still make it their business IF I were to display the ads on other pages of that site.
Ask their support to be sure. You don't wont to loose your publisher account for something like this.
I too advice you to contact Google directly. I have seen some sites do it. I am not sure whether they have got permission from Google or not.
Best place to get advice on this would be from the google helpdesk, send them an email and they will reply to your query.