"Personal identity is only partly shaped by what you call "the parental project"."
OK -partly, but mainly. That doesn't mean their personality would have been identical if they had been born from a later pregnancy, it means that when the child(ren? I think there were two) said "They could have aborted and had another pregnancy and I would have been born without the disease", the court recognised their right to use "I".
And I certainly don't downplay the environment which is far more related to the parental project than to the genes.

"It strengthens(!) my point that "the parental project" has very limited influence, and that the child has to take life as it is. The only alternative is no life."

Well, you do realise that it was the case they tried to make, and failed? So just stating it is unlikely to count as obvious evidence.

And obviously my example does not strengthen your point: the parent uses "you". If you'd been a girl, it would have been you, a different you of course. But you.

Earth provides enough to satisfy every man's need, but not every man's greed. Gandhi