So imagine, even being born as son to a King like Shantanu was a curse, and that by facilitating an early exit, Ganga bestowed a favour on her six sons! And each of you pray and long for longer life, and do not tire to be born again and again in this bhu loka. That is kaliyug, that which has screened the vision of a human being - each one is cursed and voluntarily strives to extend the period of the curse.
Ganga left, and Shantanu while wandering in forest lost his heart to the fisherwoman, Matsyagandha (who on marrying Shantanu was called Satyavati). Matsyagandha had nursed Rishi Parashar back to health, after he was injured in an attack by Sahastra Arjun. Rishi Vyas (who authored all the texts) was the son of Matsyagandha and Rishi Parashar. In today’s time, he might be considered an illegimate child, however back then there was no greater punya than rishi-seva. In fact, pleased by her service, Rishi Parashar gave her the boon to become a Rajkanya. And hence, Shantanu asked her father, for her hand in marriage. The fisherman agreed but on the condition that the child of Satyavati should inherit the throne. King Shantanu was helpless and seeing his father’s misery, Bhisma took the pledge of lifelong celibacy and got his father married to Satyavati.
Satyavati gave birth to two sons- Chitrangada and Vichitraveerya. Chitrangada died at an early age and Vichitraveerya acceded to the throne. Vichitraveerya being impotent, faced rejection in all marriage proposals. Due to this Bhishma abducted Amba, Ambika and Ambalika for marriage with Vichitraveerya. (Amba refused and asked Bhishma instead to marry her which he could not due to his pledge of celibacy. Thus Amba was reborn as Shikhandi in the Mahabharat to seek vengeance from Bhishma). Vichitraveerya died without leaving any heir (being impotent) and so Satyavati requetsted her son Vyas to carry forward the bloodline.
Likewise Vyas had three sons, Dhritrashtra with Ambika, Pandu with Ambalika and Vidur with their maid. (Vidur was none other than yamraj, who again was cursed to be born to the bhulok!) Kauravas were born to Dhrirashtra and Pandavas to Pandu. (We all know the story of Pandu’s curse, and how Kunti produced the five Pandavas with the help of different Devas).