Answer by taking a quote from the following article:

Geronimo (Mescalero-Chiricahua: Goyaale [koja:le] "the one who yawns"; June 16, 1829 - February 17, 1909) was a prominent leader and medicine man from the Bedonkohe band of the Chiricahua Apache tribe.

Geronimo was born to the Bedonkohe band of the Apache, near Turkey Creek, a tributary of the Gila River in the modern-day state of New Mexico, then part of Mexico, though the Apache disputed Mexico's claim. His grandfather, Mahko, had been chief of the Bedonkohe Apache. He had three brothers and four sisters.  His parents raised him according to Apache traditions; after the death of his father, his mother took him to live with the Tchihende and he grew up with them. Geronimo married a woman named Alope, from the Nedni-Chiricahua band of Apache when he was 17; they had three children. She was the first of nine wives. On March 5, 1858, a company of 400 Mexican soldiers from Sonora led by Colonel Jose Maria Carrasco attacked Geronimo's camp outside Janos (Kas-Ki-Yeh in Apache) while the men were in town trading. Among those killed were his wife, children and mother. The loss of his family led Geronimo to hate all Mexicans for the rest of his life; he and his followers would frequently attack and kill any group of Mexicans that they encountered. Recalling that at the time his band was at peace with the Mexicans, Geronimo remembered the incident as follows:  Late one afternoon when returning from town we were met by a few women and children who told us that Mexican troops from some other town had attacked our camp, killed all the warriors of the guard, captured all our ponies, secured our arms, destroyed our supplies, and killed many of our women and children. Quickly we separated, concealing ourselves as best we could until nightfall, when we assembled at our appointed place of rendezvous -- a thicket by the river. Silently we stole in one by one, sentinels were placed, and when all were counted, I found that my aged mother, my young wife, and my three small children were among the slain.  Geronimo's chief, Mangas Coloradas, sent him to Cochise's band for help in his revenge against the Mexicans. It was during this incident that the name Geronimo came about. This appellation stemmed from a battle in which, ignoring a deadly hail of bullets, he repeatedly attacked Mexican soldiers with a knife. The origin of the name is a source of controversy with historians, some writing that it was appeals by the soldiers to Saint Jerome ("Jeronimo!") for help. Others source it as the mispronunciation of his name by the Mexican soldiers.

Was his childhood happy?
His parents raised him according to Apache traditions; after the death of his father, his mother took him to live with the Tchihende