If you think you have a point, go ahead and make it. This isn't going to end well for you.
Definition of POSTERITY
1: the offspring of one progenitor to the furthest generation
2: all future generations
Or!
http://dictionaries.cambridge.org/define.asp?key=posterity*1+0&dict=A
posterity
the people who will exist in the future
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That's what I mean.
The word doesn't exclusively connotate the direct descendants of the speaker.
To say that the context you cite was a comment on birthright citizenship strains the bounds of credulity to a rather large degree...
Hmmm... That ended pretty well.