"People get confused between something being inherited and something being genetic. Your child's RTS is not inherited (eg. neither you nor his dad have RTS that you passed down), but it is genetic, in that a problem with a genes happened for the first time in your child and caused his RTS. Now that his genes are affected, if he was to go on to have children of his own, his children could inherit RTS from him (50%) chance).
Your chance of having a second child with RTS is quite low and represents the chance that multiple egg cells or multiple sperm cells harbor the gene change (VERY unlikely). Your other children ARE NOT at increased risk to have children with RTS. RTS is fully penetrant which means if you have the gene mutation, you show manifestations of the disorder (eg. there are no "silent carriers" of RTS).
- nothing you or your childs father did or ate or were exposed to, none of the drugs you did in college, caused this to happen.
When DNA is replicated, millions of base pairs are copied and sometimes mistakes are made.
The cell has an editing system that picks up the vast majority of these mistakes but sometimes things are missed. There is no blame to lay, this was an out of the blue thing that happened and there was nothing you did to cause it and nothing you could have done to prevent it.
The chances of anyone having a child with RTS are about one in every 200,000. Anyone could have a child with RTS.