Explain why pedigree are needed to identify the carriers of a recessive trait in a family?

A pedigree can be used to see whether a physical trait is inherited. Recessive traits are passed on to children from both parents. Characteristics are: 1) An individual affected may have parents not affected; 2) All children of 2 affected individuals are affected; 3) In pedigrees with rare traits, unaffected parents of an affected individual may be related to each other.