Question

How is the equal genetic contribution of male and female parents ensured in the progeny?

Answer 1

In human beings, every somatic cell of the body contains 23 pairs of chromosomes. Out of these 23 pairs, the first 22 pairs are known as autosomes and the remaining one pair is known as sex chromosomes represented as X and Y.  Females have two X chromosomes and males have one X and one Y chromosome. The gamete receives half of the chromosomes. 
Therefore, the male gametes have 22 autosomes and either X or Y chromosome.  

The female gamete, on the other hand, has 22 autosomes and X chromosome.  During reproduction, the male and female gametes fuse and thus the progeny receives 22 autosomes and one X or Y chromosome from male parent and 22 autosomes and one X chromosome from the female parent.