Nuclear Family

Nuclear Family is the final Institute main quest and achievement/trophy in Fallout 4.

Quick walkthrough
Talk to Father.

Detailed walkthrough
You return to the Institute to speak with Father and listen to his final words before he dies of his terminal cancer. You have glimpses of your life before the war, your experiences in a world that is ripped apart by a man-made disaster.

This short quest completes the path through the main story, and you may now continue your adventures in the Commonwealth afterwards.