We don't know for sure, but there seems to be some relations between anomalies in immune response and at least the initial presentation of the disease. It would explain a few factors that we are seeing but it's far from 'definitive' or something we can pre-determine. Just be careful if people in your direct lineage, especially males, have severe reactions. Most of the innate immune system is encoded on the X chromosome of which males only have one.

That said don't expect us to answer a lot of these questions of what is causative/predictive of a certain reaction over the long term. We don't know a whole lot about it even from prior viral outbreaks and there is a likelihood that it's partly due to sheer luck as in if the virus ever get into certain parts of your body etc. It's a bit of a shit show.