getJSON method returns 'undefined' in jquery

I am working on an Asp.net core 2.1 project and have the below model

Person

public class Person
{
    [Key]
    public int ID { get; set; }

    [Required]
    [MaxLength(150)]
    public string Name { get; set; }

    [Required]
    [MaxLength(150)]
    public string Family { get; set; }

    [Required]
    public int Age { get; set; }
}

There is a web API controller in my project that you can see it.

Web API Controller

[Produces("application/json")]
[Route("api/People")]
public class PeopleController : ControllerBase
{

    private readonly ApplicationContext _db;

    public PeopleController(ApplicationContext db)
    {
        _db = db;
    }

    [HttpGet]
    public IEnumerable<Person> GetPerson()
    {
        return _db.Person;
    }
}

Now I want to get data from my web API controller and show in index.cshtml

Index.cshtml

<h2>List Person</h2>

<table class="table table-bordered" id="list">
  <tr>
    <th>ID</th>
    <th>Name</th>
    <th>Family</th>
    <th>Age</th>
  </tr>
</table>

<script>
  $.getJSON("/api/People", function(res) {
    $.each(res, function(key, val) {
      alert(val.Age);
      var item =
        "<tr><td>" +
        val.ID +
        "</td><td>" +
        val.Name +
        "</td><td>" +
        val.Family +
        "</td><td>" +
        val.Age +
        "</td><td></td></tr>";

      $("#list").append(item);
    });
  });
</script>

Actual Json in Network Tab in browser

[{"id":1,"name":"jack","family":"bfd","age":30},{"id":2,"name":"mr john","family":"sobhany","age":36}]

But there is a problem. All data shows in my view but all values are undefined. What is wrong in my codes?