i'm mobile so bear with me here. dad's from ohio originally and went to ucla to get away from his controlling father. i didn't specify when he met his wife but it was in la. they married and after dad was finished with med school the couple moved to sf where mom is from. they had their first daughter by then and 2 more girls followed with andy bringing up the rear. dad's a general surgeon, mom's an unspecified teacher and the kids were mostly looked after by their maternal grandparents with mom and dad being an active part of their lives on the weekends. upper class and did family vacations every year, mom made sure to put them all to bed each night reading to them. they did visit ohio every year at some point but it was always strained because dad and his dad and brother (~gbrel's father) never saw eye to eye. dad also has a sister with kids (more cousins) but we again, nothing was specified. gabe looked up to their father because he's not controlling like his dad and was instead encouraging when it came to getting away from ohio and his controlling father like he did.
that's basically all the history i/we had in mind. other than that, she'd be yours to do with what you want. i figure all the siblings are close and because he he was surrounded by girls growing up, andy's always been a little more feminine which she can embrace or tease him about but ultimately i want to say they're close and he looks up to her. he's a romantic and a total optimist who wants the best for everyone, especially those closest to him.