Many, many social issues involve single-parent families. Single-parent families are at least involved in many of the most pressing social issues of our time.
One set of social issues has to do with reducing the number of single-parent families. This set of issues involves many issues itself. For example, it involves the issue of divorce because our current system in which divorce is so easy helps to cause single-parent families. It also involves issues of teen pregnancy. This is because many single-parent families come about when teens get pregnant. This means that the issue of single-parent families also involves the issue of sex education because there are deep and vehement debates about what kind of sex education should be provided to teens in our schools. It can even be said to involve the debate over abortion. It also involves the issue of a lack of jobs for blue-collar men since there are many who say that lower-income women do not marry because there are few “marriageable” men.
A second set of social issues has to do with the effects of single-parent families. Children from such families are statistically more likely to encounter many problems in life. This means that single-parent families are involved in things like poor test scores for schoolchildren. They are involved in issues such as drug abuse and excessive gang membership.
None of this is to say that all single-parent families are bad. However, the prevalence of single-parent families is, statistically speaking, related to all of these issues.