The excellent radio program Innovation Hub had an episode that dealt with various aspects of the issue of separating children from their parents at the borders, starting with how the US went from being a country with open borders to one, in the 1920s, with strict quotas.
Then it had a segment on the shocking discoveries about the extent of the permanent detrimental mental and physical effects of childhood trauma on later life. They found that children who had one or more adverse childhood experiences such as neglect or abuse or separation from parents or a parent who was depressed or suffered from substance abuse ended up being a lot sicker than others. This was not just psychologically effects such as depression but physical effects such as heart, lung, and liver disease, diabetes, fractures, cancer, autoimmune diseases, and premature death. They found that life expectancy was shorted by as much as twenty years.
Not that this information will have any effect on Donald trump and his supporters. They probably think that it is a good thing that these people suffer and die early.