4.2 Failure of passing physiological traits while human reproduction:

Father

Mother

Soccer player

Artist (painter)

extrovert

Singer

Mathematician

extrovert

Child

Soccer player

Artist (painter)

Mathematician 

Introvert

In the above example, the child missed to be a singer like the mother and missed to be an extrovert like the parents.

This is a common trouble that happens while human reproduction.

The child’s parents are not introverted then why did the child become introvert?

This is a natural phenomena and this can happen to many children.

But if the kid is not getting the appealing features from the parents it’s nothing but a problem. The child became an introvert.

 The medical experts still can’t cure these issues.