If the 14 billion year history of the universe were compressed to one year, and "now" is exactly midnight December 31, approximately how long ago were your grandparents born?

About 0.15 seconds ago

Explanation:

The universe was created about 14 billion years back after the big bang explosion, and right from that time, the universe is expanding at a certain rate and there released the Cosmic Microwave Background (CMB) radiations.

If this 14 billion years history of the universe were compressed to one single year, then the earth was formed by the month of September and life originated on earth by the end of September.

The "present-day" or "now" would have been on the 31st of December at midnight, and our grandparents were born about 0.15 seconds back.