Forced Apologies

The following is not based on research, only on my own opinion of requiring your child to say "sorry":

Telling someone you are sorry means you regret your actions, are publicly declaring it, and asking for someone to acknowledge it by forgiving you. This concept is first of all too difficult for a child to comprehend (it is our duty as parents to teach our children what is right and what is wrong, however it is important to note that small children do not comprehend what right and wrong means, they only understand consequences their parents provide, this is also why lying is such a problem--they know that lying will save them from getting in trouble and by telling the truth they will face punishment, it IS that simple!
Secondly forced apologies end up meaning nothing to the child. By requiring your child to say sorry it is very easy (for them) to do and not punishing, which means they are likely to repeat the behavior. If they have a consequence attached to their behavior they are less likely to repeat the behavior.

Here's a tip: instead of forcing your child to give a half hearted apology, tell them they must fix what they have done wrong (you may want to wait until your child is 3 or 4 to do this)If your child hits their sibling, they must do something for their sibling to make up for it(ex. make their sibling's bed, pick up their toys)