Question

how equal contribution of male and female parents ensured in progeny ​

Answer 1

During sexual reproduction, a femalegamete (having 23 chromosomes) fuses with a male gamete (having 23 chromosomes) to form zygote. Zygote is diploid which contains 23 chromosomes from mother and 23 from father. In this way, an equalgenetic contribution of male and female parents is ensured in theprogeny.

Answer 2

As the child born have XX or XY pair of chromosome out of which X sex chromosome is inherited from mother and X or Y is inherited from father