Sean Lio Weston (born January 13, 2004) is the youngest child of Andrea and Fred and the little brother of Andrew.

Sean was an active baby who was often in harm's way. This was due to his jealous older brother, Andrew constantly terrorizing and bullying him. At night, Sean had trouble sleeping because Andrew would disturb him with his bedtime games. Sean was eventually given his own room so that Andrew wouldn't wake him up at night.

At the end of the episode, Sean took his first steps.

He was 11 months when he appeared in "Supernanny".