All of my kids still come & chat to me while I'm in the shower, including my 13yo son & 15yo daughter.. ok, so they don't get in with me, but I don't think you have to worry about scarring them, if you leave it up to them as to what they are comfortable with you're pretty safe.
They are all very modest when it's them showering / bathing, but me...meh, I'm a mum ... they seem to think I'm immune, privacy? What privacy?

FWIW I think we stopped showering / bathing together around 4 -6 years...soemthing like that. They will definitely let you know
lol oh yeah WHAT privacy huh! I do love that your kids are that comfortable with you that they come and talk to you

My 2 little ones come and go in and out lol. Oskar is 4 in March and still wants to sometimes shower with me. My eldest (17) will stand near the door and call out if he wants to ask something but doesn't come in.
y