Repositories, factories and hierarchically structured data

I am going through Domain Driven Design by Eric Evans where he outlines the interplay between Repositories and Factories. The repository itself will call an DB interface to get a result set. This result set would then be passed to a factory that would understand that result set to reconstitute the object.

What if the data was hierarchical in nature, like some sort of tree structure. For example:

public class Foo
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Foo Parent { get; set; }
    public ICollection<Foo> { get; set; }

    // Other business like methods here

}

Using DDD I would have my interfaces and implementations:

public interface IFooRepository
{
    Foo Get(int id);
}

public interface IFooFactory<TSource>
{
    Foo Create(TSource source);
}

public class SqlFooRepository: IFooRepository
{
    private readonly IFooDao dao;
    private readonly IFooFactory<SqlDataReader> factory;

    public SqlFooRepository(IFooDao dao, IFooFactory factory)
    {
        this.dao = dao;
        this.factory = factory;
    }

    public Foo Get(int id)
    {
        var resultSet = dao.Find(id);
        return factory.Create(resultSet);
    }
}

public class SqlFooFactory: IFooFactory<SqlDataReader>
{
    public Foo Get(SqlDataReader reader)
    {
        var foo = new Foo();
        foo.Id = (int) reader["id];
        foo.Name = (string) reader["name"];
            // Do I build the children accounts here
        return foo;
    }
}

If I try to build the children in the factory then I need access to the repo again. If I do it in the Repo I feel like I am doing work that should be for the factory. Not sure how to tackle this one.

One thought I had is that the Foo is not the aggregate root but rather the FooTree is the aggregate root. So trying to get any Foo I would need to create the entire tree, which means I could pass a collection of Foo objects to a FooTreeFactory.

Any help would be very appreciated.