Cyrille:

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.

It's an amazing, bizarre case, the more I think about it. The parent can't simply declare using these words that it would be you. It is short for "if this pregnancy had turned out to result in..." What if the child is unhappy about, say, its gender? Can it sue because the parents didn't make sure it's a girl? Why not?

Am I obliged to feel identical or something with the embryo that my mother aborted after having Rubella? I refuse. It's not me. What power has this embryo to force me? I can't imagine it will sue.

Cyrille:

"Your sons probably would care"
Why?

Children need to know who their biological parents are, and during adolescence they need to transform the role of both sets of parents if there are social parents as well. It's one of these psychological needs of every human being that can't be avoided. They would never forgive you, if you lied to them about that. I am a foster mother of two, btw.