Is anyone else bothered by the fact that some day somewhere down the line one of your children’s children will produce a child that will have none of your genes?
There will be nothing of you left.
I’m a happy person living a happy life and this thought has kinda thrown a monkey wrench into my serenity. I’m losing sleep over this 
Two very important things can be drawn from this:
Finding meaning exclusively in any one source is a bad idea. Particularly if that source is a poorly defined one with a limited scope.
Worrying about things in the distant, distant future is a recipe for sadness. You may as well worry about the heat-death of the universe.
That’s where ethnic/national/race pride comes in. At least you will know that your descendents will likely still belong to your “tribe”.
If you were dead, what difference would it make?