public class Person
{
    public string Name { get; set; }

    public int Age { get; set; }
}

public ObservableCollection<Person> Collection { get; set; }

public List<Person> Persons { get; set; }

private void WindowLoaded(object sender, RoutedEventArgs e)
{

    this.Persons = new List<Person>();

    for (int i = 0; i != 35; i++)
    {
        this.Persons.Add(new Person() {Age = i, Name = i.ToString()});
    }

    this.Collection = new ObservableCollection<Person>(this.Persons);
}

<Grid DataContext="{Binding ElementName=TestWindow, Path=.}">
    <DataGrid x:Name="DataGrid" ItemsSource="{Binding Collection}" />
</Grid>

<Grid DataContext="{Binding ElementName=TestWindow, Path=.}">
        <DataGrid x:Name="DataGrid" ItemsSource="{Binding Persons}" />
</Grid>