Why is it cute?

Please forgive me for the parent moment I'm about to share, but I need to in order to support my question. Why is it that normally gross or annoying things are magically transformed into being cute when done by your child? For example, the other day Emma was going potty and doing her business, when from the other room Eric and I starting hearing some rather loud grunts. Normally I don't like hearing noises from the bathroom, but from Emma they were so cute! We just started laughing at how hard she must have been working in there. And it isn't just in the bathroom that odd things are cute from kids. Why is this? You know, the messy face after eating sometimes, the messed up crazy hair, any mess really, mismatched clothes, miscellaneous bodily noises (at least when they're little). I don't know if it's because they are small, or because they are your children and you can't help think they're adorable, or both. In the end I don't really care why it is. It's just one of those things I wonder about sometimes.