Where does this tone of voice come from?

I got a call from my nephew.

As I spoke with him, I noticed my tone of voice changing. My usual nonchalant, dry voice is gone, and it has become warm, tender, and a little bit sweet. It almost feels like I’ve suddenly become a daycare teacher.

It’s something that usually doesn’t come out. Not even with my husband. I don’t really try to do it, and I’m not even really conscious of it. It just comes out like this. Listening to myself, I feel like, “Why is this woman talking like this?”

Why does talking to my nephew change my tone of voice? Is it because I’ve known him since he was a baby?

Every time I talk to him, my own voice surprises me. What’s up with this, seriously?