Earlier quoted context omitted.
Not depressed or suicidal, just realising they have no right to gamble with another human being's life.
An honestly held belief that their child would have a miserable, depressed, ill life I could understand - especially because those traits can be heritable. I can also understand sour grapes. However the other arguments seem very ill-motivated.
> An honestly held belief that their child would have a miserable, depressed, ill life I could understand
There's always a risk of that, unless you can 100% guarantee this won't happen you're basically gambling with another person's life. I don't think you have the right to do that.