It's important to recognize that toddlers are not quite at an age to be capable of empathy, as these are still concepts that are new to them. Young children learn from watching, especially when it comes to manners and other socially-based actions. If you have more than one child, the best way to avoid early tantrums and conflict is to buy multiple items of the same type for each child to prevent jealousy. As they get older, lead by example and ALWAYS positively reinforce good behaviour. For example, if you ask for a bite of the child's cookie or to see their toy and they comply, make sure they realize how much you appreciate this with a big "THANK YOU!" This makes the child feel good about what they're doing and will likely encourage them to continue that behaviour.