They may seem contrary, impossible to handle, and constantly opposed to anything parents say or do. This is how they assert their growing independence. A child's emotional development can be affected by the limits parents set. The toddler that never gets to touch anything may, at an older age, not feel free to do anything. On the other hand, a world with no limits can lead to serious injury and foster a spoiled child who never learns boundaries.
Balance is the key.
Do not be overprotective or under-protective. Allow toddlers to self-test and explore. Comfort and reassure them when things go wrong. A child's sense of right from wrong develops gradually. At first, they fear parental disapproval, so their undesirable behaviors are not continued.