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What will Pop be behind in? Expectations as to what s/he does or does not like?
And its not a secret from the CHILD, just from everyone else. Pop knows there is a difference and as soon as Pop cares to say what gender s/he is s/he will. Right now, being very small it doesn't matter to Pop. I think the parents point, and I agree with them, is that it shouldn't matter to anyone else either.