My PIL are naturists. My FIL in particular. He always wears as little as possible, generally a t-shirt and boxers. It's a bit odd, but I've got used to it now.
My DH was brought up in a naturist environment and has slowly converted me although I was brought up in a household where nudity was taboo - I can't remember ever seeing my Mum in the nude, let alone my father 
I love that in our household if it's warm there's no rush to get dressed in the morning and we went to a naturist camp in France last year and once I got used to it it was really nice. No trying to get dressed in a too small tent, getting sun cream/sand in clothes, etc. Children thought it was great too.
But. My PIL have just moved to a house with a swimming pool and it's just getting warm enough to use it. Last time we visited we were sitting on the veranda when I saw my DC whizz past (in the nude) followed by a nude FIL to go swimming. DH followed them in, also in the nude. I managed to avoid seeing anything but WIBU to ask FIL to put on swimming trunks when I'm there, bearing in mind that DC and DH are also in the nude? And since I suppose IABU has anyone got any ideas how to manage things as I'd quite like to swim (with a cozzie on) as well but there's no way I'm going in while he's in the pool in the nude!