Girls of age

What is the difference between girls aged:
8, 18, 28, 38, 48, 58, 68?

At 8 - You take her to bed
and tell her a story.

At 18 - You tell her a story
and take her to bed.

At 28 - You don't need to tell her a story
to take her to bed.

At 38 - She tells you a story
and takes you to bed.

At 48 - You tell her a story
to avoid going to bed.

At 58 - You stay in bed
to avoid her story.

At 68 - If you take her to bed,
that'll be a story!!

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