Many website owners are confused about Google adsense adult content policy. They by mistake place adsense code on pages containing content which is not adult but also not family safe. As It is clearly indicated in Google adsense policy that you must have family safe content for your adsense website.
Now doubt is which content is considered Family Safe?
Family safe doesn’t just indicate the absence of adult or p0rn0 images. It should also be safe for viewing by children. It’s not only limited to images, text or links present on your site but you should not also receiving links from sites which are meant for adult. I know of an incident where a wordpress theme developer, who provide free wordpress theme in exchange of a link from the footer of the theme back to his site. He got warning message from Google for getting links from adult site. I don’t know rest of the story, what he did after that but i think he must update his theme or removed ads from that page but As we all know receiving links from other sites can’t be controlled it’s not in our hands, still we must be aware who are linking to us.