Is a person's reticence with his father and his not sitting and talking with him considered an act of disobedience, especially if this is simply the person's nature?

If the father is not bothered by his daughter's lack of conversation with him, then this is not considered disobedience (ʿuqūq); because disobedience occurs through causing harm, and if harm is absent, then disobedience is absent. It is recommended to keep company with the father and bring joy to him due to the righteousness it entails and the attainment of Allah's pleasure and love, and to avoid future regret. The nature of isolation can be changed through struggle (mujāhadah) and effort, for virtues are acquired, as stated in the Hadith: "And whoever strives for patience, Allah will make him patient," and "Knowledge is only acquired through learning, and forbearance is only acquired through striving for forbearance."