Which of the following is not true regarding "thumb sucking" :

Thumb sucking Normal in infants and toddlers. It peaks between the ages of 18-21 months and most children spontaneously drop the habit by 4 years. Can lead to dental malalignment. Parents should be reassured and asked to ignore the habit if child younger than 4years. If child 4-5 years, the parents should motivate the child to stop thumb sucking and encourage him when he restrains himself. Application of noxious agent in thumb is found useful. Reference: GHAI Essential pediatrics, 8th edition