New study says that there is no such danger as long as the children receive love and affection from the parents.

The researchers found that strict discipline did not have any negative effect on the teenagers as long as a mother was warm and provided love and affection to her children.
However a number of parenting groups and charities have said that smacking should not be an option for parents to discipline their children. “Someone might say, 'What's a little smack?' But in a society where there is violence and the parent is the strong model for the child, the use of smacking is not something that we want to encourage for children. You can get such wonderful outcomes by helping children make decisions that are right — not making decisions because they fear being punished or getting a reward”, Early Life Foundations’ Dr Shona Bass said.
Source-Medindia