Is it normal to add my professor’s daughter as a friend on facebook?

Last semester, I curiously looked up my accounting professor on Facebook after the first day of class. Not only that, but under his profile section, he had his family members listed, including his daughter. I thought the daughter was somewhat attractive so I sent her a friend request, and the next day, I noticed she had accepted it.

Now keep in mind I have not spoken to or messaged her since I added her and I have never met her in real life, and I also never told my professor that I found him and his daughter on Facebook.