Kylie, Tyga, Rob, Blac: One Big, Messy Family Tree

Not trying to give y'all a headache ... but imagine -- if Tyga ever slipped one past the goalie with Kylie it would create some pretty kooky familial relationships ... with King Cairo and his soon-to-be sibling at the center of it all.

We banged our heads and unraveled how things might look ... hypothetically, of course. Follow the maze ... try not to get lost in translation.

- Tyga and ex, Blac Chyna, spawned King Cairo ... he'll be half brother to Rob and Chyna's unborn kid. Tyga then becomes an uncle to Cairo's new half sibling ... by virtue of Rob and Kylie's sibling relationship.

- If Tyga and Kylie popped out a kid ... that'd give Cairo another half sibling ... Tyga and Kylie's hypothetical kid would be half cousins with Rob and Blac's kid.

- Rob would be Cairo's stepdad ... and an uncle to Tyga's and Kylie's kid -- with Blac as aunt to King Cairo's half sibling.