I had a good idea: In order to take 'universal traits' you have to take a 'quirky flaw' to balance it out.
basicly a flaw could be: a complex about breast-size, Inattentive, short, accident-prone (in the bad 'burning hot soup in the lap of protagonist-kun' sorta way) etc.
it'd be a nice balance and it'd give the characters more 'life' to them if they have something that's not perfect or below sub-par. this could of course also be something like 'chronic sickness' where you either get a penalty to athletic rolls or a total ban on doing such (maybe a heart condition or severe asthma).
but hey, i just enjoy playing a girl with nicely-sized assets