In The Sims 3, Erin reappears as a toddler, living with her family in Aurora Skies. Erin is 3 days from being a child, but comparing her age to her brother in The Sims 2, she would already have been a child, while her brother would have been close to becoming a teenager.
When the game starts, Erin has a positive daily relationship with Kristen, and a positive but low relationship with Lola. She has a negative daily relationship with Chloe, who seems to have a slight dislike of her and Kristen. She most likely inherited her green eyes from her maternal grandfather Leif Halfdanarson.
Erin's older brother Loki lives in the Beaker household with his wife Circe and test subject Nervous. Their parents are Bjorn and Gundrun Beaker, both deceased and also of Strangetown. Erin was born when her brother was a child.