There are strong statistics and studies which prove that the optimal environment for a child is a healthy home with a mother and father, this is also what is recommended as per Islam. There was also studies which showed that people who commit crimes are more often raised in single homes vs people who do not commit crimes.
I learned this in an optional sociology course at University, broken homes = broken kids = broken adults.
In terms of Obama I think you fail to consider the strong role his White Irish Grandparents played in his upbringing, they pretty much raised him, he mentions them over and over in his book “The Audacity of hope”. He especially mentions the important role his Grandfather played in his life.