Bruer 1999 has criticised those who regard the early years as having particular significance in lifelong development and suggest that parents should ignore warnings to the contrary. He suggest that damage is reversible - a view shared by others. However most theorists warn that although there are very few critical periods - periods of time when if children fail to develop in particular ways it will be difficult or impossible for them to do so later- failure to meet those that may be found to exist may have serious implications. Siegel 1999 for example suggests that if attachment fails to take place in the first year,it will be difficult to replace at a later stage. Bruer 1999 concludes that 'parents should realize that children thrive in a wide variety of physical and environment and learn and benefit from experiences throughout their lives.