Why is it horrible that I bathe with my children?

My sister was camping in my house with her children as well, our kids are the same age, 2 years old and 3 month olds, I said I was gonna jump in the bath with the kids and she freaked out saying that they will see me naked and be traumatized, I always bathe with my son and baby girl, because I'm a single mum with no help at all and never have time to shower alone so we all ju.p in and igs just much easier to get all of us clean and dressed at the same time, is it wrong? I dont think its gross, my babies dont seem to mind, we always play with toy boats and the splash animal toys and the bath colouring stuff, I'm just kind of appalled that she would think this way?