Traditionally you have a cause, and following that, a consequence. This is set in stone.
Cause (A) - Consequence (B)
If you were to expand on that, a consequence can be the cause of a new consequence.
Cause (A) - Consequence (B) - Cause (C) - Consequence (D)
or
Cause (A) - Consequence/Cause (B/C) - Consequence (D)
However!
Let's say that for whatever reason, the consequence affects the past.
That could create a scenario where the consequence predates the cause, even as it follows the cause.
Consequence (B) - Cause (A) - Consequence (B) - Cause (C) - Consequence (D)
Note that 'both' consequences are one and the same.
Now what if it turns out this consequence directly influences the cause? In other words, it would be causing the cause.
Consequence/Cause (B/A) - Consequence(B)
This means the consequence is the cause to itself.
Consequence/Cause/Consequence (B/A/B)
If you were to now create the order of sequences, since both B's are the same, you'd get an infinite repetition.
B/A/B/A/B/A/B/A/B/A/B-infinity
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Here's the stickler, because of time travel, time does no longer move exclusively forward. Because B is a consequence in both the future and the past, it now moves two ways! Which means every time A happens, a B must happen before it, and an A must happen before the B, etc. This creates a two-way infinite repetition.
infinity-B/A/B/A/B/A/B/A/B/A/B-infinity
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No matter how far you try to go back, or how far you try to go forward, it keeps going. Which brings us back to the beginning, namely our perception of time.
Because we naturally perceive that time moves forward, we have no problem grasping that there's no ending to this order of sequences.
But because we aren't used to time moving backwards, we have a lot more trouble accepting that there's no beginning to this order of sequences, even though it follows the exact same reasoning as to why there's no ending either.
And that, is why baby Jane has always been, and will always be, the child of John/Jane.