Your mom is kind of overdoing this. Your daughter is learning how to use the potty. It has nothing to do with sex at age 1.
I have a 10 yr old an a 5 yr old an a 19 month. My 10 an 5 r girls but my son is tge 19 month old an he still showers with me. An sometimes takes a bath with his sister. He doesn't even notice a difference. As long as ur not making a big deal out if it then they don't even know.
My son sees me in the shower regularly. He's 3.5. Children need to see a human body, there's nothing wrong with it. Making out that certain parts are "bad" or "secret" just causes confusion.
I have a 2 year old daughter and she's such a daddy's girl she will follow him to the bathroom too! He makes sure she can't see anything and I have no problem with it! They are little they have no idea what privicy is! I say as long as he's covered its fine