intelectual freedom and parents advisory in the library

At least a few times a week at the Linden Tree bookstore where I work I will see a child with a book intended for an elder age bracket. As it is our role to promote all the books we can, I simply allow it to happen given the parents approve and that the parents know basics of the book. The same works for all media materials especially in a public library. I look forward to my first experience on the service end of a public library in my internship next semester. But based on everyones comments I can see how we have an overwhelming consensus on that it is the parent's responsibility to be the gatekeepers to what their children are allowed to experience/learn. For one clear reason, parents are legally responsible for their child till the child turns 18 and librarians are not. As strong believers in intellectual freedom, I believe it it is any public librarians duty to open all peoples minds (help all people learn) and grow everyones imaginations. This means everyone also has the freedom to check out anything, but kids are legally "guarded" by their parents, and parents are responsible for their kids. 

I think the main reason parents complain about content of books is that the parents themselves are unaware of the material's content until it is to late to keep the child from "exposure" to undesirable content. I think it is as many (all) of us do that parents need to be fully aware of the content or at least subject matter of the books they are letting their kids read. Parents need to always play a proactive role in defining appropriateness of the materials their kids are experiencing, lest their kids grow up "too fast" or any other criteria (as defined by each individual parent).     

In terms of dealing with the parent who takes issue with the librarians lack of legal responsibility (liability) for their child,  I would simply remind them it is not a librarian's job to impede on the freedoms of anyone.