Physical factors such as; exercise

Genetics, down syndrome can hinder a child's development.

Nutrition, a healthy diet can improve a child's development.

If the factors I mentioned above are not taken care of properly, despite the amount of parents in the home, the child's development will be changed. Many people have looked into the difference between single parent homes and two parent homes, and there wasn't a difference. Unless an outside factor such as a new spouse to the single parent, in which case some children were affected. When a new person comes into their mother, or fathers, life the children grow up in an unstable environment. Which can have long term effects that might require the child to go through therapy in the future. This instability can cause the child to grow up indecisive and have other major effects on the child. Even though the child of a single parent home can grow up with some troubles, so can two parent children. A child who is subjected to arguing, in either home, will be traumatized and when they grow up will have issues as well. No family is perfect, and every child grows up in different circumstances that are unique to him or her, so to say that two parents is always better is inaccurate, and incorrect.