If I take you literally, you just eliminated ~half the population (average).I already said that I think a person needs to evaluate themselves that they have average physical stamina, i.e. they come home from work and they could spend several hours doing chores and such without feeling severely fatigued or mentally out of it.
Again, here, if I use the literal sense of average, half the population wouldn't be suitable.If they have average mental health or control enough of a mental condition that they have average mental function on a regular basis and that they have dealt with any issues of dysfunction or denial mechanisms that they learned growing up. That they have good work habits and a marketable skill that they can support themselves on with enough to spare for a child too.
That's what I'm asking - a literal definition of what is suitable. If I don't take your answer literally, I'd end up saying that you are looking for functional, which isn't a good measurement in my eyes.
If I was going to do that, I'd say that the bottom 30% or so of earners shouldn't raise children. Or a certain age. I could use all forms of statistics to come up with an argument that only about 5% of the population should breed, based upon inhereted traits, bad genes, IQ, financial reasons and social position. I feel that argument would be stronger than a subjective interpretation of what an individual can cope with.
It's easy to say when there are obvious cases... but the line between obvious and not so obvious is very blurry and contains more factors than I could calculate.