At what age do you stop letting your kids touch your breast?

I’m mostly curious about this, and other parts of your body. For example, I shower with my son (20 months old). I do avoid letting him touch my vagina. But if he does I try not to react so he doesn’t become more curious. I usually just casually move out of the way. He still touches my boobs. He stopped breastfeeding around 14 months. I don’t let him touch them (bare) if I’m dressed. But if we’re in the shower or I’m getting him dressed and mine are out I don’t stop him because it was very normal for him to nurse for a long time. I’m curious on when I should start being more firm about touching. I want to try to stop showers together soon, but it’s hard to take a shower while watching him. So I just bring him in with me.