In this world, time travel is possible, but the only thing that can be sent back in time are thoughts. From the perspective of your past self, you suddenly one moment realize that you have "memories from the future" -- more precisely, a knowledge of "what if", and more "wisdom" since you're spiritually suddenly older.
Given that you have different knowledge than you would if you didn't send your memories back in time, that without a doubt means that you would do things differently, at least slightly. You cannot mimic the precise way you did things before because you're concious about it. The moment you receive memories from the future, a new "timeline" is spawned, because the butterfly effect undoubtly propagates from your different decisions/actions, meaning that the future won't be precisely the same as you remember it, and it will just keep diverging more and more as the time progresses.
In this chaotic interpretation of the world, where even the slightest change in its structure is bound to propagate into a completely different outcome, how does that affect genetics?
My actions can make a couple have sex a few minutes/hours/days earlier/later, but would the result be the "same" child? The unpredictable nature of this world means that the child won't grown in the same enviornment, so he will (probably) grow up into a completely different person from the psychological point of view, but what about his genes?
Would a person's genetic signature be exactly the same if he was concieved at a different point in time, from the same parents?