Who married the children of Hazrat Adam?

Adam as children were born twins(one male and one female).The Sharia of Adam as was different at the time.Allah created them as twins.there were many twins born to Adam and Eve pbuth.

Each twin was forbidden to marry the twin partner.

They were allowed to marry other member from other twins.

The first ever murder took place because one of the sons of Adam tried to marry his own twin partner and killed his brother who was supposedly marrying her his twin partner.(read Habeel and Qabeel story)

I think SALAFI has talked about everything what you need to understand. I shall add one more think that it was temporary marriage in the Sharia (Law) of Adam just for a purpose of population which was forbidden in the next era.