Randall, I have to wonder if that father had unrealistic expectations for his son and whether he might have been more concerned about social stigma than his son's ability to assimilate a new culture and worldview.
Do you known of any specific ways in which the son's (or the father's) view of reality was false and not just a different-but-valid perspective?
Agreed that culture plays a role in how we interpret things such as whether bugs are icky or yummy, bathing is good for you, gods cause thunder, animals have souls, people should be obedient cogs in society or rugged individuals, disease can be cured by drugs or incantations, women are intelligent human beings with full rights or nothing but chattel.
But a lot of who we think we are is based on biology, not culture. The experience of motherhood, warfare, grammatical language, emotions, and sensory perceptions are common to people everywhere.
The brain generates the sense of self from core consciousness and autobiographical memories, so of course the "self" changes over the years as the contents of memory change. The autobiographical memory contains all the absorbed cultural knowledge with which we transform sensory information into "experiences" that are consistent with our belief system. If we assimilate ideas from another culture, we can use them to re-interpret prior experiences and perhaps change our world-view.
Suppose that you decide that everything you once believed is wrong and completely reassess and reconstruct your own reality. How do you know that the assumptions on which you based your new world-view get you any closer to Reality than your old ones? If their brand-new illusions make people happier, perhaps it is best not to examine them too closely.