I have 15yo B/G twins. They came out of me and I also breastfed. They'd follow me in to the loo. Nothing was ever private with those two!
I distinctly remember them both bending down to get a better look at me weeing in a public toilet once (I squat to wee in public toilets). Lots of questions were asked, especially when I needed to change my tampon in a public loo!
Therefore, I don't bat an eyelid about nakedness around them. I don't flaunt it but if I need to run downstairs to fetch a bra or something, while I'm naked then I will. Neither child bats and eyelid about nakedness but they do check if it's ok if they can come in when I'm in the shower or on the loo before they come in now. They're not fussed if I see them on the loo but, again, wouldn't do it on purpose, it would just be if they forget to lock the bathroom door or something.
My girl isn't bothered about me seeing her naked but she doesn't like her Dad or her brother doing so which I think is natural. My boy doesn't usually care if anyone in the house sees him naked. My girl hates it though so I've been firm with him about respecting her boundaries as it's important for them both to learn that know means no and to respect each other.
Their Dad is a bit more uptight and thinks that I shouldn't be naked in front of them but I take my lead from them because of their age. But, to me and then seeing each other like that is natural because we've always done it.
DH never did any of the grunt work after they were babies so they're not used to seeing him naked nor him them by the time our girl was about 8, so they'd find it weird to see him naked.
I'm quite an open book with them as it feels natural to me. There's very little that they haven't seen of me!
I have also done all of the sex ed stuff from when they were preschooler's and asked questions because DH squirms at the thought of even talking to his son about it. I'm even talking to our son now about shaving as my DH squirms at that! My Dad has bought my son his first electric shaver. My belief is that you get out what you put in and DH wonders why they aren't particularly attached to him.
My parents weren't really naked parents. I saw them a couple of times but they wouldn't wander around the house naked. I remember being really surprised to see my best friend walking around in her bra and knickers as a 16 year old in front of her Dad and brother and it seemed normal to them. I didn't realise that other families did that!
So, I trust my own gut and take the lead from my kids.