Re: 2yo DD Touching Lady Parts. .
I just explain that private parts are not for playing with, they are for peeing with. And pee is gross. So let's not put our hands on our private parts, or put our private parts on other things. And that's pretty much EXACTLY what I say about it.
At the same time, this goes hand-in-hand with teaching good/proper hygiene, and encouraging open communication about body parts. My 6 y/o knows not to play with her private parts, but she also knows that if she has a question about them, I am here to answer them for her.
Naked time (except for babies) is reserved for bathroom breaks, changing your clothes, and bathing. Otherwise, I encourage them to be dressed and covered, even at home.
It doesn't have to be a big deal if you don't make it one. I don't punish for exploratory touching in babies. It's silly. But I do redirect, distract, and say "No - our private parts are for going potty, and they have pee pee on them..." etc.
I have 3 kids and so far none of them have had trouble keeping their hands off their private areas. I think just communicating with them can help a lot. But it's a delicate balance between - "Your vagina is DIRTY" and "Let's not touch ourselves that way please."
...as they get more vocal, it gets more complicated... lol.