The mechanism by which the sex of an individual is determined is called sei-determination. In human beings, sex of a newborn is genetically determined, whereas in some others it is not. There an 46 (23 pains) chromosomes in human beings. Out of these, 44 (22 pairs) control the body characters and 2 one pair are known 25 sex chrumosomes The sex chromosomes are of two types - X chromosome and Y chromosome At the time of fertilisation depending upon which type of male gamete fuses with the female gamete, the sex of the newborn child is decided.
Why is a pair of sex chromosomes in human beings called a mismatched pair in terms of type and size?