Entity Framework Code First — почему при создании отношения one to many, в таблице создаются 2 колонки?

public class Article
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public Guid Id { get; set; }

       ...

        public virtual ICollection<Comment> comm { get; set; }
    }

public class Comment
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public Guid Id { get; set; }
        public Guid ArtId { get; set; }
        
       ...

        [ForeignKey("ArtId")]
        public virtual Article art { get; set; }
    }

public class Article
    {
        ...

        public List<Comment> CommentList { get; set; }

        public Article()
        {
            CommentList = new List<Comment>();
        }
        ...
}
public class Comment
    {
        public int ID { get; set; }

        public int ParentID { get; set; }

        public string FullText { get; set; }

        public string Author { get; set; }

        public string Email { get; set; }

        public DateTime DatePublication { get; set; }

        public Article Article { get; set; }
        ...