My husbands brother had malignant melanoma, is there an increased chance that he would get it ? or our children ?

Melanoma: Yes. Melanoma has a genetic component. All direct relatives should be aware of watching for skin changes that could predict cancer.

Melanoma : There is a slight increase in the risk of melanoma for your children and husband. Check any new orchanging moles.

Here's the key: These do tend some to run in families. Please be sure all his blood relatives keep a close watch on their skin and have any suspicious lesions removed early. Do this, and the chances of dying of melanoma are very low.