Lol. No, seriously, this is fun.
Can I kill cripples?
Are they "fully realised" people?
Gays? Pretty sure I could define homosexuality (especially without the intent to breed or adopt) as lacking "full realisation" of the human condition.
The uneducated? Are they "fully realised"?
The spiritually barren?
How about kids with Down Syndrome? I'm sure you'd advocate preventing their existence while they're still in the womb, for convenience' sake, but how about after they're born? They're still a burden, so the only question is: are they "fully realised"?
Heck, I bet it wouldn't be too hard to justify defining a woman who doesn't want to be a mother as not being "fully realised". Can I kill her?
Is someone who is not "fully realised" the same as someone who has not reached their potential? Much like the unborn fetus has not reached its potential. If that's the case, we might as well just kill everyone.
Though, maybe it would be better to kill people who
are "fully realised". I mean, when you've reached the top, attained full realisation of your human potential, what's the point in going on? Might as well make room for someone with a bit of room to grow.
Or maybe "fully realised" is the same as fully-formed?
I think we could get into all sorts of interesting moral places if that's the case.