Portia and Jessica have both been subjected to their fathers' restraints. Although Portia is a strong, independent woman, her filial loyalty is unshakeable and, although she may try to manipulate the choices of her suitors, she is prepared to marry according to her late father's wishes:
"so is the will of a living daughter curbed by the will of a dead father" (I.ii.24-25).
Portia is something of a contradiction; a seemingly loyal daughter, a strong-willed character and even a cruel manipulator, despite her christian virtues creating a complete and believable character, making her loyalty to her father all the more admirable.
Jessica feels aggrieved by her father "Our house is hell … " (II.iii.2) and plots to run away at the next possible instance. The stark difference here is that she does not feel any filial loyalty whatsoever and can't wait to cast the ultimate betrayal - when she converts to Christianity. She shows no respect and even belittles a precious item her father, Shylock gave her, which belonged, apparently to her late mother.
Elizabethan audiences would have seen the justice in Jessica's actions and frowned on Portia if she had shown the same disdain for her father. Shylock is the stereotypical Jew and the audience would have believed him to be an ungodly character.
Shylock's religion and the memories of his late wife are the things that define him and his affection for the item Jessica so cruelly swapped give him human qualities and make audiences warm to him slightely. Clearly, Jessica knows what will upset her father so has done these things, trying to hurt him , presumably because of his uncaring attitude towards her but also to satisy the needs of the audiences of the day.