Question: Who is the father of the person developing Bust of Pope Gregory XV?

full_context: Document 1: Aeneas, Anchises, and Ascanius: Aeneas, Anchises, and Ascanius is a sculpture by the Italian artist Gian Lorenzo Bernini created c. 1618-19. Housed in the Galleria Borghese in Rome, the sculpture depicts a scene from the "Aeneid", where the hero Aeneas leads his family from burning Troy.
Document 2: Bust of Cardinal Giovanni Dolfin: The Bust of Cardinal Giovanni Dolfin or Delfin is a sculptural portrait by the Italian artist Gian Lorenzo Bernini, which is part of a mausoleum for the Venetian Cardinal Giovanni Delfin, member of one of Venice's most ancient noble families. The tomb as a whole was a joint work commissioned of Bernini and his father Pietro. While Gianlorenzo executed the portrait bust, Pietro carried out the surrounding figures, including two allegorical figures of Faith and Hope as well as the Delfin family coat of arms. The work was completed in late 1621, and sits in the church of San Michele in Isola.
Document 3: The Goat Amalthea with the Infant Jupiter and a Faun: The Goat Amalthea with the Infant Jupiter and a Faun is the earliest known work by the Italian artist Gian Lorenzo Bernini. Produced sometime between 1609 and 1615, the sculpture is now in the Borghese Collection at the Galleria Borghese in Rome.
Document 4: Bust of Gabriele Fonseca: The Bust of Gabriele Fonseca is a sculptural portrait by the Italian artist Gian Lorenzo Bernini. Executed sometime between 1668 and 1674, the work is located in San Lorenzo in Lucina in Rome, Italy. Gabriele Fonseca was the doctor to Pope Innocent X.
Document 5: Bust of Pope Gregory XV: The Bust of Pope Gregory XV is a marble portrait sculpture by the Italian artist Gian Lorenzo Bernini. Executed in 1621, the work is one of three busts of the subject created by Bernini—the other two were bronze casts. The marble bust is on permanent display at the Art Gallery of Ontario. It was donated to the museum by Joey and Toby Tanenbaum.
Document 6: Bust of Camilla Barbadoni: The Bust of Camilla Barbadoni is a marble sculpture by the Italian artist Gian Lorenzo Bernini. Executed in 1619, it portrays the (deceased) mother of the Maffeo Barberini. Camilla had died in 1609. Barberini would become Pope Urban VIII in 1623.
Document 7: Charity with Four Children: Charity with Four Children is a sculpture by the Italian artist Gian Lorenzo Bernini. Executed between 1627 and 1628, the work is housed in the Vatican Museums in Vatican City. The small terracotta sculpture represents "Charity" breast-feeding a child, with three other children playing. There is an imprint of the artist's thumbprint in the clay.
Document 8: The Rape of Proserpina: The Rape of Proserpina () is a large Baroque marble sculptural group by Italian artist Gian Lorenzo Bernini, executed between 1621 and 1622. Bernini was only 23 years old at its completion. It depicts the Abduction of Proserpina, who is seized and taken to the underworld by the god Pluto.
Document 9: Bust of Thomas Baker: The bust of Thomas Baker is a 1638 marble portrait sculpture created by the Italian artist Gian Lorenzo Bernini, with much of the bust undertaken by a pupil of Bernini, probably Andrea Bolgi. It is currently held in the Victoria and Albert Museum, London, who purchased the bust in 1921 for 1480 English guineas.
Document 10: Bust of Antonio Cepparelli: The Bust of Antonio Cepparelli is a sculptural portrait bust by the Italian artist Gian Lorenzo Bernini. It was executed around 1622. It is in the museum of the church of San Giovanni dei Fiorentini in Rome.
Document 11: Sleeping Hermaphroditus: The Sleeping Hermaphroditus is an ancient marble sculpture depicting Hermaphroditus life size. In 1620, Italian artist Gian Lorenzo Bernini sculpted the mattress upon which the statue now lies. The form is partly derived from ancient portrayals of Venus and other female nudes, and partly from contemporaneous feminised Hellenistic portrayals of Dionysus/Bacchus. It represents a subject that was much repeated in Hellenistic times and in ancient Rome, to judge from the number of versions that have survived. Discovered at Santa Maria della Vittoria, Rome, the "Sleeping Hermaphroditus" was immediately claimed by Cardinal Scipione Borghese and became part of the Borghese Collection. The "Borghese Hermaphroditus" was later sold to the occupying French and was moved to The Louvre, where it is on display.
Document 12: Bust of Francesco I d'Este: The Bust of Francesco I d'Este is a marble portrait bust by the Italian sculptor Gian Lorenzo Bernini. Completed in 1652, the work depicts Francesco I d'Este, Duke of Modena. It is in the Museo Estense, Modena, Italy. The noble yet detached expression of the face, the extensive drapery and the lavish locks of hair are often taken to be emblematic of the way Bernini represented 'absolute monarchs' as seemingly adopting superior poses, oblivious to their surroundings. A painting of the portrait bust, surrounded by various objects, undertaken by the artist Francesco Stringa in the late 1660s is in the Minneapolis Institute of Art.
Document 13: Bust of Francesco Barberini: The Bust of Francesco Barberini is a marble sculpture by the Italian artist Gian Lorenzo Bernini, now in the National Gallery of Art in Washington, D.C.. It was executed in 1623. It was commissioned by Pope Urban VIII, who was nephew of Francesco Barberini, an apostolic protonotary. Francesco had actually died in 1600 so Bernini created the bust from an existing painted portrait. The painted portrait is in Corsini Collection in Florence; Bernini made close use of the design, although the painting was a three quarter portrait as opposed to a bust of head, shoulders and upper body.
Document 14: A Faun Teased by Children: Bacchanal: A Faun Teased by Children is a marble sculpture by Italian artists Gian Lorenzo Bernini and his father Pietro Bernini. It was executed in 1616 and 1617, when Gian Lorenzo was not yet twenty years old. It is currently in the Metropolitan Museum of Art in New York.
Document 15: Bust of Giovanni Vigevano: Bust of Giovanni Vigevano is a marble sculptural portrait by the Italian artist Gian Lorenzo Bernini. The bust was produced between 1617 and 1618, and was then inserted into the tomb for Vigevano after he died in 1630. The tomb is in the church of Santa Maria sopra Minerva in Rome.
ground_truth: Pietro Bernini
sub_queries: Who developed Bust of Pope Gregory XV? Answer: Gian Lorenzo Bernini
Gian Lorenzo Bernini >> father Answer: Pietro Bernini