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In different animals the sex of the progeny is determined in diferent ways ;
-
After fertilization, in some animals, the
temperature at which the eggs are kept determines the sex
of the progeny.
For Example - Turtles, Alligators, Crocodiles
Thus in such animals, sex is determined by environmental conditions
-
Snails
, on the other hand, can
change their sex
.
This means that in snails, gender is not genetically determined -
In case of
human beings
;
Human beings give birth to male and female children due to genetic reasons.
-
- Human beings have 23 pairs of chromosomes.
- This makes a total of 46 chromosomes.
- Out of the 23 pairs, 22 pairs (44 chromosomes) have a copy from the mother and father each .
-
But
1 pair
called
the sex chromosome
, is not always paired perfectly.
- Women have a perfect pair - both are X - XX (Egg)
- Men have one normal sized X chromosome and another short chromosome called Y chromosome - XY (Sperm)
- So,
- This means that there is a 50% chance that the child is a male or female.
- Though the sex is determined by which gene is inherited from the father , the process in completely by chance and the probability of the child being male or female is equal.
