As Pandu passed many years in the forest, he wanted children badly as he had heard that a man with no sons was doomed to go to hell. He wanted Kunti to produce a child in the same way his mother had done. Kunti would have none of it. Pandu could not rest in peace and spent his time in misery. Finally taking pity on the king she loved immensely, Kunti relented and spoke to him about her childhood and of the boon granted by sage Durvasa. The king's joy was immense. They chose to have a son born to lord of Dharma and so Kunti invoked the lord. The child born was named Yudhishthira, personification of Dharma himself. The king was a very happy man.
Year later they had another son, fathered by Vayu, the most powerful of the devas. He was called Bheemsena, who would be most powerful and affectionate. The king wanted another child and Kunti obliged by invoking Indira, the lord of heavens. He was named Arjuna and Indira proclaimed: 'This son of mine will be the conqueror of the entire world'.
Pandu wanted even more sons! Kunti did not agree as she said 'desperate acts are allowed only three times at the most'. Pandu suggested that she teach Maadri the chant and also help her to get a son. Maadri invoked the Ashiwini kumaras, the heavenly twins. The sons of Maadri were called Nakula and Sahadeva. Voices from the heaven said, 'They would be the most handsome in the world and full of good qualities, bravery and wisdom'.
The children grew up in the forest and were taught the skills in the use of arms by Suka, a famed archer, who was doing penance in the forest. Thus the young prices became proficient in the use of weapons. Bheema was good with the mace. Yudishthira in the use of Javelin, the twins with the sword. Arjuna became a good archer.
(The basic urge to have off springs is programmed in to our genes. While 'Niyoga', the practice of inviting rishis/gods while accepted was still a desperate act and surely traumatic. Luckily there are many methods of assisted pregnancy now.
With the increase in world population, I wonder if our genes would be modified and there would be no instinctive urge to have children. However for nature to evolve such a genetic code would be a long way off. The process must be on as many couples now opt to have less children and a few have opted not to have any. Thus establishing the role of intellect and the ability to make choices.)
(There is also the case of China where it is coerced.)