Johannes Kepler was born on December 27, 1571, a premature child. To be precise, according to his own records, the pregnancy lasted 224 days, 9 hours and 53 minutes. (This rather odd piece of information, and the quotes from Kepler's horoscopes for his family given below, I found in Koestler's book, reference 1.) It should be clear from this obsession with the precise time of birth and conception that Kepler took astrology fairly seriously. He was born in Weil, in Swabia, a wine region in southwest Germany not far from France. Unfortunately, the family he was born into makes Tycho's early life look tranquil by comparison. Kepler's grandfather was Mayor of Weil, Kepler describes his grandmother as "restless, clever and lying, but devoted to religion; slim and of a fiery nature; vivacious, an inveterate troublemaker; jealous, extreme in her hatreds, violent, a bearer of grudges...and all her children have something of this". His father he describes as "...a man vicious, inflexible, quarrelsome and doomed to a bad end. Venus and Mars increase his malice. Saturn in VII made him study gunnery..." Kepler's mother he describes in the family horoscope as "small, thin, swarthy, gossiping and quarrelsome, of a bad disposition". His mother collected herbs and made potions which she believed had magical powers. She was raised by an aunt who was burned at the stake as a witch, and Kepler's mother narrowly escaped a similar fate herself (see ref 2, page 159: Kepler had to hire several lawyers to defend his seventy-year-old mother incarcerated on a charge of witchcraft, and "Another woman born in the same town as Kepler's mother, and accused of complicity with her, had already left one of her thumbs stuck in the rack".)
As a seven-month child, Kepler was sickly from birth, and contracted smallpox when very young. His vision was severely defective, and he had various other illnesses fairly constantly, some of which may have been hypochondria. He took twice as long as normal children to get through elementary latin. He did a little better when he got to the higher school at Maulbronn, a school which only half a century earlier was haunted by the ill-famed Dr. Faustus (ref 2).
Kepler went to the University of Tuebingen, a Protestant institution, where he studied mainly theology and philosophy, but also mathematics and astronomy. (The Dukes of Wuerttemberg, after becoming Lutheran, put in place an efficient educational system, with grants and scholarships for the poor, to ensure the universities could supply well educated clergymen capable of defending the new faith in the religious controversies raging at the time.) At the university, Kepler's exceptional intellectual abilities became apparent. He greatly admired the astronomy professor Maestlin, who publicly taught the Ptolemaic scheme, but privately believed Copernicus. Kepler himself defended Copernicus' scheme in a public debate. Unfortunately for him, that ensured that he would not be offered a faculty position at Tuebingen when he graduated. (Luther himself had mocked at Copernicus' scheme, and quoted scripture to prove it wrong.) Instead, Kepler was offered a professorship of astronomy in faraway Graz, Styria (now part of Austria), where he went in 1594. One of the duties of this professorship was to make astrological predictions. Despite his earlier efforts at horoscopes, he wrote "a mind accustomed to mathematical deduction, when confronted with the faulty foundations (of astrology) resists a long, long time, like an obstinate mule, until compelled by beating and curses to put its foot into that dirty puddle" (ref 1, page 245). Nevertheless, he predicted a cold winter, and an invasion by the Turks. Both predictions turned out to be correct. He was treated with a new respect, and his salary was increased.