Dark: Question about an important plot?

SPOILER TO THE NETFLIX SERIES "DARK"!

I'm currently on the seventh episode of the first season of Dark and in the fifth or sixth season it was revealed that Mikkel Nielsen is Jonas' father.

It seems to be a running circle here, because everything should have happened before, but how can Jonas have been born before Mikkel, but still be his son?

As I said, I'm currently on the seventh episode of the first season.

Should it be explained in more detail, please don't spoil me.

It will be explained in the second season

Thanks, that's enough for me!

I just didn't want to look any further while I don't really understand a big, important plot.