<human>: Peter Brian Gabriel was born on 13 February 1950 in Chobham, Surrey. His father, Ralph Parton Gabriel (1912-2012), was an electrical engineer, and his mother, Edith Irene (nee Allen), who was from a musical family, taught him to play the piano at an early age. His great-great-great-uncle, Sir Thomas Gabriel, 1st Baronet, served as Lord Mayor of London from 1866 to 1877. Gabriel attended Cable House, a private primary school in Woking; St Andrews Prep School in Horsell; and Charterhouse School in Godalming from 1963.

Gabriel's departure from Genesis on 15 August 1975, which stunned fans of the group and left many commentators wondering if the band could survive, was the result of several factors. His stature as the lead singer of the band and the added attention garnered by his flamboyant stage persona led to tensions within the band. Genesis had always operated more or less as a collective, and Gabriel's burgeoning public profile led to fears within the group that he was being unfairly singled out as the creative hub. The band also began to feel confined by the reputation (and fans' expectations) attached to their famously elaborate theatrical performances, believing that the visual element of their performances was receiving more attention than their music.  Tensions were heightened by the ambitious album and tour of the concept work The Lamb Lies Down on Broadway, a Gabriel-created concept piece that saw him taking on the lion's share of the lyric writing. During the writing and recording of The Lamb Lies Down on Broadway, Gabriel was approached by director William Friedkin, allegedly because Friedkin had found Gabriel's short story in the liner notes to Genesis Live interesting. Gabriel left Genesis to pursue a film project with Friedkin, only to rejoin a week later. The decision to quit the band was made before the tour supporting The Lamb Lies Down on Broadway, with Gabriel explaining his decision to the band while keeping it from the press until the conclusion of that tour. Bassist Mike Rutherford recalled that they all "could see it coming". Although tensions were high, both Gabriel and the remaining members of Genesis have stated publicly that Gabriel left the band on good terms.  The breaking point came with the difficult pregnancy of Gabriel's wife, Jill, and the subsequent birth of their first child, Anna-Marie. When he opted to stay with his sick daughter and wife, rather than record and tour, the resentment from the rest of the band led Gabriel to conclude that he had to leave the group. "Solsbury Hill", Gabriel's debut single as a solo artist, recorded in 1976 and appearing on the Car album in 1977, was written specifically about his departure from Genesis. The song reached the Top 20 in the UK Singles Chart, and also charted on the Billboard Hot 100 in 1978, reaching No. 68. In 1982, Gabriel reunited with his former Genesis colleagues for the one-off concert Six of the Best, to recoup debts that arose from his involvement in the staging of the first WOMAD concert. CANNOTANSWER

Using a quote from the above article, answer the following question: How many children did he have?
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