Congrats on your acknowledgement that you enjoy being nude! A lot of adults that enjoy nudism started the same way you are.
Nudism is not a career choice (in most cases) so most people who enjoy nudism have to be clothed when appropriate, like when you are around others who do not enjoy nudism, or when you go to school or work.
With your grandparents being foster parents, they may have to limit your freedom around the house to maintain their ability to remain foster parents. So even if they agree that it is not a big deal, they may not be able to allow you to freely be nude around the house....
It sounds like your grandparents are very open minded and would not freak out over an open conversation. If they do, you can always acknowledge their position and resume your current activities.
Did you know Ben Franklin enjoyed being nude, he use to call it taking an "Air Bath"
Being nude is not pornographic, there are nudist organizations that promote social nudity and have a code of conduct that tells people what proper behavior is, while in a nudist environment, www.AANR.com. There are lots of nudist clubs in Ohio, look here http://aanr.com/stateclubs/aanr-oh.html
Keep in mind that there are some adults who will portray themselves as teens for bad reasons, so use extreme caution when communicating with people online, never give your real name, address or phone number. If you decide you want to communicate with someone from one of these sites, by phone, letter or in person, PLEASE, be honest with your grandparents and let them help you make the contact in a safe way, with an adult with you.
If you are skinny dipping with older people from the neighborhood, there should never be inappropriate touching or talk about sex, that would be a good indication that you should not continue skinny dipping in their presence!
Stay safe, look out for snapping turtles!
Famous Nudists (So you know you are not alone...)
These are people who are known to practice non-sexual nudity at home or have visited nude beaches or other places for nude recreation.
Lara Flynn Boyle
Melanie Brown (Spice Girl)
Paul Daniels (magician)
Flea (Bassist - Red Hot Chili Peppers)
Ian Gillian (Lead Singer - Deep Purple)
Cuba Gooding Jr
Melissa Joan Hart
Kate Humble (BBC presenter "Autumn Kate")
Mollie King (British singer/musician)
Queen Latifah (Dana Owens)
Sir Ian McKellen
Sheryl Lee Ralph
Princess Stephanie (Monaco)
Adrian Young (Drummer - No Doubt)
John Quincy Adams
Robert A. Heinlein
Patrick "Tip" O'Neal
Henry David Thoreau