It’s an incredibly varied disease, and no, it’s not necessarily time-related. It’s a progressive illness (confusingly, even the relapsing remitting variety is progressive), which, in general, means people will get worse the longer they’ve had it. But rate and extent of the deterioration is hugely variable. There’s nothing about it that’s the same for everyone - except, perhaps, the uncertainty of not knowing how bad it might get, or how soon. We all have to live with that.
It is definitely NOT hereditary, and/or hereditary with skipping generations. Where there’s a grain of truth, though, is that it does tend to cluster slightly in families. This is subtly different from heredity, because although blood relatives of an affected person are slightly more at risk than the general population, there is no “MS gene” that can be passed on. The true causes of MS are not yet understood, but it is accepted it must be due to a complex interplay between genetic and environmental factors. That means people (blood relatives) who share a lot of the same genes might have a stronger predisposition towards MS, but does NOT mean they will all get it. Genes are only part of the story. You might have genes linked with a higher risk of MS, you might not. But there is no one gene or set of genes that can predict who will get it. Even if you have several genes that have been associated with higher risk, it does not mean it is your destiny to get it. Most people with the “risky” genes still won’t.
Hope this helps,