You knew it but as a society we probably can't talk about it enough: married bio parents are better for kids than other random family arrangements.Family structure and living arrangement.
Family structure reflects the number of parents in the household and their relationship to the child; living arrangement reflects their marital or cohabitation status. Considering both factors, the NIS–4 classified children into six categories: living with two married biological parents, living with other married parents (e.g., step-parent, adoptive parent), living with two unmarried parents, living with one parent who had an unmarried partner in the household, living with one parent who had no partner in the household, and living with no parent. The groups differed in rates of every maltreatment category and across both definitional standards. Children living with their married biological parents universally had the lowest rate, whereas those living with a single parent who had a cohabiting partner in the household had the highest rate in all maltreatment categories. Compared to children living with married biological parents, those whose single parent had a live-in partner had more than 8 times the rate of maltreatment overall, over 10 times the rate of abuse, and nearly 8 times the rate of neglect.
Not all traditional families are good for all kids but taken as a large population, this is the best solution to many childhood hazards.
Fourth National Incidence Study For Child Abuse And Neglect - Report To Congress