My cat seems to love me more when I'm in the bathroom?

My cat Ziva is a little over a year old, and for as long as we've had her (since she was eight weeks), she's liked us best when we're trying to use the toilet.

Ziva is not a cuddly cat, never has been. She dislikes being held; attempting to pet her usually results in her biting or running away; and if she wants to hang out with us, she sleeps on a blanket or piece of discarded clothing near us rather than on our laps. However, as soon as I go into the bathroom, she wants in. If she can't open the door, she paws at it until I let her in. Once she's in, she rubs all over my legs, demands to be petted, and often jumps up on my lap. It's a little awkward, but I let her do it because it's the only time she's the cuddly cat I thought she was when we brought her home. As soon as I leave the bathroom, she's back to being the same aloof kitty she usually is.

She is our only pet. We try to give her lots of attention, but she doesn't want it (unless we're trying to poo). She's always been curious about what we do in the bathroom, but she isn't like this when I'm brushing my teeth or getting in the shower.

Is there something I can do to redirect this behavior, or this is just a Ziva-specific quirk I have to live with? I don't mind, but my mother is pretty disturbed about the whole thing, haha.