How to cast all child elements in an unlimited hierachical data ?

This is how my class looks like

public string Id { get; set; }
public string Name { get; set; }
public string Surname { get; set; }
public string StudentNo { get; set; }    
public object Subjects { get; set; }

and i want to cast all Subjects object to a newly created Subject class

How can i achieve this ?

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19karabo91