Likes Older Women: At least one episode has him competing with Dave for the affection of his teacher. At the end of the episode he decides that older women are too much trouble, only for him to gain a crush on his new babysitter. In the second live-action movie he flirts with highschool girls.
Mommy Had A Good Reason For Abandoning You/Parents as People: Was a single mother, left her three baby chipmunks on Dave's doorstep because she genuinely couldn't support the four in a particularly snowy and cold winter. At one point, she did try to get them but sees how happy they are with David, so she decides to leave them.
It's difficult to determine, as her hair seems to change color, depending on the animation, coloring, etc; while her hair does appear red on some occasions, it mostly appears light brown, and in even rare occasions (merchandising) blonde.
Proper Lady: Not only is she never once seen to get angry about anything, and is the most calm of the girls, but in the episode when the six kids had to work out which of them was at fault for a broken statue in their school, she wasn't even a suspect.
Cloudcuckoolander: Sometimes has strong traces of this, especially in A Chipmunk Adventure, though it's considerably toned down in later seasons as she becomes established as the parental figure for the Chipettes.