It is proven that any major change in a child's life greatly affects their development. Adoption is quite a significant change which will affect the child in some way.
Depending on the stage at which the child was adopted will again determine how much of affect it will have. For instance a child at two months is going to be affected differently from a child at seven.
Lets say, for arguments sake, that a child only a few months old is going to affected minimally compared to a child is in the middle of their primary development. So it is therefore children in the primary age of the spectrum we are going to be considdering when we think about this.
Changing the environment that any child has been in for a while and has become accustommed to has an affect on them. And that is what adoption does, it takes a child from one environment into a new, but however permanent one. And permanent is the key word here.
If adoption agencies placed children anywhere and everywhere that would totally negate everything I am about to argue for. However since adoption agencies in general do tend to have a high set of standards before placing children with parents the majority of what I am about to write is true and valid for the majority of cases.
Yes adoption affects the child's development, but I would argue that in the long term it is, ultimately, beneficial for the child.
At the beginning of the child's stay in the new environment there will be a period of unrest. This is natural, the child has been taking out the surroundings it once knew and placed into new unfamiliar surroundings. During this time the child may could become despondent. And this will affect their development for however long this period of unrest lasts for.
In this time it is important to continually nurture the child, help them to settle into their new surroundings. Talk them and help them evaluate for themselves what would help. You would be surprised how including children in helping to find a solution to help them will work. It always important to give children a say and let them be heard. That helps them to communicate their feelings and thoughts which helps in the long run. Also in doing that it is something meaningful for them and by providing a meaningful interaction with children it helps their development.
After this initial period I believe it is all up hill from there. Yes your adopted child will go through all the same stuff every other child does and ups and downs will happen. In terms of their development tho there will be nothing to worry about.
I say that because the environment they would have been placed in will be a nurturing and loving one. Both of which are everything a child needs to develop well. Adoption takes a child out of uncertainty into a place of stability, care and love. And that is why in the long term it is better for a child's development.
Yes adoption affects a child's development, but in the long run it will benefit their development because it brings them into a stable environment which enables the child to develop to their best potential.