Okay, so I am new to RPG's both as a player and as a GM. I own most of the rule books for Rogue Trader, Only War, Black Crusade, Dark Heresey(1st e) and Deathwatch. My family has finally agreed to entertain the idea of playing one of these games with me. I like to think that I have a decent amount of knowledge with the 4ok universe, but my family has none. I will have both male and females players. up to three players total. I was wondering if there is any suggestions as to which universe to introduce them into the 40k universe while also keeping it easy for all of us having no RPG experience. (I mostly collected the books for a personal collection point in hopes eventually I'd find someone to play with). Any suggestions or feedback is greatly appreciated.

That depends on the family. Give them a brief description of the WH40K universe from the perspective of a member of the imperial guard, a rogue trader, an acolyte, and a worshipper of chaos.

If any hits home go with the perspective system.

Depends on how old your kids are, too. Rogue Trader is, thematically, the most open and family friendly. Both Black Crusade and Dark Heresy are not things I would play in their entirity with a younger audience. Deathwatch would work as well, but people not familiar with the fluff often find it a bit goofy, while everyone can relate at least peripherally to an "explore and trade" type game.

Depends on how old your kids are, too. Rogue Trader is, thematically, the most open and family friendly. Both Black Crusade and Dark Heresy are not things I would play in their entirity with a younger audience. Deathwatch would work as well, but people not familiar with the fluff often find it a bit goofy, while everyone can relate at least peripherally to an "explore and trade" type game.

"Trade" as in, trading macrobattery shots?

I like how the Rogue Trader ship mechanics can be added to every other 40k RPG line.

Or as in, where you are handed a prayer book, a torch, a vagabond-class transport, and a condition to peacefully convert a world to imperial creed in a decade, or your warrant is gonna be nullified, but once you arrive you see that locals never even heard about "Imperium" and have prospered for the last ten millenia while worshiping chaos gods.