Choroidal neovascular membranes (CNVM) are new, damaging blood vessels that grow beneath the retina.
The most common causes are age-related changes, trauma, very high glass power more than 6D etc.
If the reason is high glass power (high myopia) - it has hereditary association.
Next Steps
glass power of your kids and thorough retina examination by a pediatric ophthalmologists should be checked.