Question

Sex of a human child is determined by the:

• A. Size of the egg at the time of fertilization
• B. Size of the sperm at the time of fertilization
• C. Sex chromosome of the father
• D. Sex chromosome of the mother

Answer 1

The correct option is C Sex chromosome of the father

Gametes of the mother (eggs) contain only X chromosomes while gametes of the father (sperms) contain 50% X and 50% Y chromosomes. So, the child will have one X chromosome from the mother and another X or a Y chromosome from the father. Offspring with XX chromosomes will be a girl and the offspring with XY chromosomes will be a boy.

Therefore, the sex chromosome of the father determines the sex of the child.