The one-time toxic twin has a soft spot for kids.

The insane and legendary partying of Aerosmith vocalist Steven Tyler and guitarist Joe Perry earned them the nickname "The Toxic Twins."  Nowadays though, they would rather spend time with their family and fans than drugs and alcohol.

Tyler, a father of four and grandfather of two, especially likes kids.  When he found out the little girl sitting behind him on a flight was having a birthday, he turned around and sang happy birthday to her.  The girl's mom posted it on YouTube with this message:

Steven Tyler sits in front of us on Southwest and took my phone to sing Happy Birthday to my daughter on her 7th birthday and this is what happened…what a great guy!!! So cool and now she is also a fan for life!!”