What is the father-son relationship in The Vendor of Sweets?

The relationship between the Jagan and Mali in The Vendor of Sweets is not a very strong one.

Part of the reason for this is cultural.  Jagan represents the traditionalist values of Indian identity.  He wears homespun cloth.  He looks at the wall that features a picture of the Goddess Lakshmi, who controls wealth accumulation.  He tries his best to fuse his way of life with strict Gandhian principles of adherence to spiritual truth.  Jagan carries with him the legacy of being a freedom fighter in India's struggle against the British.  It is for this reason that he cannot easily surrender his past and what it means.  The struggle for those values were real and represent priorities that are dear to his heart.  

Mali does not share these values.   He is different as he embodies much of the youth in India.  He fails to acknowledge Indian/ Hindu traditions that he sees as "backwards."  He sees his life as his own and not linked to anything larger. It is for this reason that he sets his mind to going to America, taking money from his father without consent to do so, and setting up abroad.  On a personal level, the relationship between father and son is frayed because Mali blames his father for his mother's death.  The differences are stark when Mali returns back to India.  He feels that the country of his birth is foreign, as “He seemed to cower back and recoil from the bright Indian sunlight.” He has returned for financial fain and nothing more.

The generational gap differences between father and son help to contribute to a frayed relationship between them.  The communication gap between them is even more difficult to overcome.  Jagan cannot bring himself to effectively speak to his son, while Mali did not even write the letters that his father brandishes about with beaming pride.   Their relationship is shown to be incapable of overcoming the intense differences between them.

What causes the strained relationship between the father and son in The Vendor of Sweets?

I think that though the strained relationship between Jagan and Mali—the father and son at the heart of R. K. Narayan’s The Vendor of Sweets (1967)—is a result of clashing personalities and value systems, the roots of Mali’s dislike for his father go back to a particular series of events in their history. To understand the trigger that soured their relationship, we have to visit the scene of the death of Ambika, Mali’s mother. Through Jagan’s narrative, we learn of that “terrible Friday” when their doctor has been in attendance of his wife for 48 straight hours, armed with “needle, oxygen, and icebag.” Ambika has a rare, fatal form of brain cancer, and her end is near. Mali, just a child at the time, is watching the proceedings, his “thin, scraggly frame” almost too harrowing for Jagan to stomach. Mali has been especially attentive to his mother in her last sickness:

He had been attending on his mother for several weeks now ... he came running home from school in order to feed her, rarely going out to play with his friends.

Through Jagan’s account we see a startlingly different, tender Mali, so different from the cold, taciturn young man the novel introduces. What has happened to Mali? We know he is capable of sensitivity, so why then does he not extend the same tenderness to his father? The answer has something to do with Jagan’s peculiar notions about modern medicine. As the doctor leaves their home that awful Friday night, having done all he could to relieve Ambika's agony, we are told he has been driven nearly mad by “Jagan’s hint that Nature Cure might have benefited” his wife.

Jagan mistrusts modern medicine almost pathologically and is a firm believer in herbal remedies. Earlier, in an eerie foreshadowing of Ambika’s condition, we see Jagan refuse to give her aspirin, even as she sits with a towel knotted around her temples to relieve a terrible headache, swaying “madly back and forth in pain.” But Jagan suggests she should instead fry a little “margosa flower in ghee and swallow it for relief from the headache.” This is described as the first fight of their married life, with Jagan claiming Ambika has always hated his propensity for natural remedies and his penchant for special diets. However, Jagan is finally forced to fetch her aspirin and asks Mali where his mother keeps her “headache pill.” But when Mali shows curiosity about the pills, Jagan's fear that Mali might consume them leads him to say something strange to the child. No doubt, Jagan's odd warning to Mali has something to do with his own revulsion for Western medicine.

“Boy, don’t you go near it; it is poison."

“What’s poison?" asked the boy innocently, looking up from the paper kite he was fiddling with.

"Oh ... people die when they eat poison.”

The retelling of these events is subtle and leaves it for the reader to draw inferences. When Jagan gives Mali’s mother a pill he terms “poison,” little does he understand the association Mali’s brain forms, which is that his father is poisoning his mother. It is also suggested Jagan’s obsession with “Nature Cure,” led him to ignore Ambika’s serious symptoms and prolong her agony. For Mali, his father’s peculiar, antiquated ways begin to represent the cause of his beloved mother’s suffering and untimely death. Therefore, his father's values and way of being start appearing malicious to Mali. Mali’s feelings are never spelled out as such, but are symbolized in the way he metaphorically and literally shuts himself off from his solicitous father.

Later in the novel, Jagan will repeat the same pattern. Thus, the mother’s death represents a critical fracture in Mali’s relationship with obtuse but well-meaning Jagan, from which it never heals.

As well as the age difference, Jagan and his son have radically different value systems. Jagan prides himself on his deep spirituality and his commitment to the old ways (though it's a fairly shallow commitment, it must be said). Meanwhile, Mali is much more overtly materialistic. He's not interested in the values of the satyagraha movement to which his father once belonged; he just wants to lead an opulent Western lifestyle with all its luxurious trappings.

The main difference between father and son is that Jagan is more adept at hiding his greed beneath a mask of spirituality. Mali, for all his faults, is at least refreshingly free of hypocrisy. One can only speculate, but perhaps Jagan finds it so difficult to get along with his son because he acts as an uncomfortable reminder of what Jagan himself is really like beneath his phony spiritual surface.

In The Vendor of Sweets, the generation gap between father and son strains their relationship.

When Mali speaks reproachfully to his father that “Oh, these are not the days of your ancestors” and when Jagan says that the younger generation “are not the sort to make a home bright," it reflects the gulf that exists between father and son.  Jagan is a follower of Gandhian values, a man who suffered physical abuse for his role in the Indian Independence Movement.  He struggles with balancing the spiritual with material.  For example, while he sits and reads the Gita, he also secretly counts his money from his sweets business.  His son, Mali, does not experience this struggle.  Mali is driven by materialism.  He steals his father's money to live and study in America and returns to India simply to start his own business.  Mali is modernistic, and has disdain for his father's cultural and spiritual approach to life.

The relationship between father and son is frayed because neither is able to understand the other.  Mali has little care for what his father believes.  For his part, Jagan's emphasis is on resolving the battle between material and spiritual.  He seeks to move closer towards a spiritual way of life.  As the novel ends, Jagan is able to surrender the bonds of this life and is preparing for his next phase, one for which his son has little care or regard. There is little emotional connection between both men because they believe in different generational ideas, with no chance of reconciliation.