Mark is the only son in the family, but his father is not an only child.

There is an uncle in Mark's family, and logically speaking, the inheritance of the his family should have belonged to the uncle, as the uncle's talent in these matters is indeed greater than that of Mark's father.

Unfortunately, Mark's uncle had an illness in the past, and was unable to have children after the surgery.

Mark's uncle adopted a daughter, who is the younger sister that Mark ...