I am going to give a rough presentation on twin studies. The terms heritability and concordance are included already, but I struggle with understanding the difference of the genetic material of dizygotic twins and ordinary siblings.
While ordinary siblings evolved from different sperm and egg cells, I only know that dizygotic twins form when two different sperm cells fertilize egg cells of the same cycle. However, I'm not sure if these cells are identical products of the same meiosis process.
I appreciate your help and time.