It is believed that height of a child depends upon the genes inherited from parents.However,it is seen that tall parents have short children and vice-versa.Are there factors other than genes,that can cause these variation?

Yes, It is not necessary that if the parents are tall the child will also be tall. It can change depending on many environmental factors. Some times a child can grow tall if he is indulged in many physical activities. Diet can also affect variation. Some times there are inborn errors in the child and so on. Climate,lifestyle,etc  also affects variations.