i know this might spark some controversy. however my father suffers from mental illness and so do I. My psychiatrist explained that mental illness can be hereditary and there are studies done which supports this fact. so i'll leave this out for everyone as a discussion. should people with mental illness be more incline to not have children knowing that their offspring will be more susceptible to experiencing mental illness?
There's a bit of nuance to this. Mental illness itself - let's take depression as an example - isn't inheritable. Factors that increase risk to develop depression, are.
Watch out lol, wall of text that is only interesting if you like the subject...
Take for example the gene for the serotonin transporter. Serotonin is an important neurotransmitter that is involved in all sorts of processen in your brain, but most people know it for it's influence on our mood. Now there's two types of this gene - a long a short version. So you can have two short genes, two long genes or one short and one long gene for the serotonin transporter. People that inherit two short versions of this gene tend to (thus not always) react more intensely to all situations - so they laugh louder for example, but they also experience more intense sadness or grief when something negative happens as opposed to people with two long versios of this gene. It is this more intense sad reaction to negative events that makes these people more likely to experience depression in life.
But! That is only if you experience said negative events. I'm not talking about not getting the toy you wanted when you were little, think more like traumatic events such as losing a significant other or experiencing bullying. So they have an increased risk, but it is not predetermined that these people will experience depression.
In the end though, mental illness is influenced by so many factors.
Excuse me if there's any mistakes in the wall of text above. I'm no neuropsychologist haha.