Helminths are contagious, it has been documented again and again that good hygiene and proper disposal of feces, urine, phlegm help to decrease the entry of eggs and the growth of helminths in humans.
But the numbers of eggs which manage to develop as larvaes and then to full adults depends on the immune system cells available weapons and defense mechanisms as well as the state of the channels of elimination.
For example, your husband may have immune system cells which have weapons and defense mechanisms to damage/kill or/and evacuate the kind of helminth you are infected with, and your children may have inherited this too, but your body is a different organism.
Another possibility is that they may be infected but their immune system is able to keep the load low enough so it does not cause annoying symptoms.
This is why you can sometimes see some people who are affected by a virus/bacteria/helminth while others who live in the same enviromnent are not.
Then there are also several others parameters to consider (diet, habits, activity) which can influence the state of your immune system and of your channels elimination.
The danger with helminths is that, once they have managed to grow to larvaes or adults, they have ability to trick the immune system and to weaken the detection/response mechanisms so that they are not attacked by the immune system cells.
And then it becomes a vicious cycle. You eliminate less, you assimilate less nutrients, they produce more waste in your body, they produce irritations, cuts, you are more susceptible to be infected, you have more annoying symptoms, etc...
That is why the idea of relying on a strong immune system to be protected from helminths may not be enough in some cases, because depending on the helminth kind and if the load is high enough then the immune system detection/response mechanisms will be altered/weakened so...