The sex offender's registry includes those who have committed a host of serious and disturbing crimes. However, it also includes some less troubling ones. For example, a drunk man urinating outside a bar may get charged with indecent exposure and, therefore, be on the list. Thus, it's important to know the specific charges that landed the father on the registry.
With that being said, it's not beneficial for any child to be around a parent who's a poor role model. First and foremost, youngsters should be protected from any possible harm: physical, emotional, and psychological. Moreover, they need an honest, age-appropriate explanation of why their dad isn't a part of their lives. They blame themselves without proper information, wrongly believing that they did something that's keeping Daddy away.
Little kids certainly don't benefit from hearing all the gruesome details of their father's crimes. However, they do need to know that he hurt people and is being punished because of it. They need to know that our legal system is making sure that he doesn't harm anyone else.
Youngsters also need an apology from their mothers for picking such a low-quality person to be their dad. This is the all-important teachable moment that's often hard for moms. However, their kids need to know that picking a partner isn't a crap-shoot. They need to know the mistakes that their mom made, whether it was not knowing him long enough, having sex too early in the relationship, or being attracted to bad boys.
Kids need to be reassured that they have the power to choose a decent partner when they're adults. This gives them hope for their futures.