What are the odds that the other 2 siblings will be affected from the cephalic disorders that have already affected two of my children?

my 3 year old son has been diagnosed with polymicrogyria (no seizures though ) amongst other things like ADHD, SPD, Speech delays, IBS, with even some autistic features. Now we also had a baby that passed at birth from hydracephaley. we were told that it was so rare that it would never happen again. I'm just now finding out these two are linked. My husband has gram mall seizures ( a few every month ) but never been diagnosed epileptic. Is this genetic through him because of his condition ? Also, we have 2 more boys at home ( younger ) what are the odds that there could be something wrong with them as well?

[mammo]

You truly need to get a geneticist involved to answer all your questions and explain why this is happening.  They are your best resource and you need to know all the facts and this is who can give them to you.  Take care..