Isaac had a sister Sarah who was was married in 1611 to Degory Priest and married a second time in 1621 while in Leiden in the Netherlands. Sarah sailed to the New World in 1623 on the ship "Ann". She died in 1833 in Plymouth. See https://www.werelate.org/wiki/Person:Sarah_Allerton_%281%29

In 1627 Isaac was elected by his fellow colonists to return to England to negotiate with the investors of the merchants who funded the New World endeavor in Plymouth. His goal was for the colonists to buy out the merchants for Plymouth. 
<<<<< LOTS MORE ON ISAAC & HIS FAMILY IN SAVAGE'S NE.GEN.DICT. >>>>> <<<<< LOTS MORE ON ISAAC & HIS FAMILY IN AMERICAN ANCESTORS ARTICLE ON MAYFLOWER FAMILIES >>>>>

Per the article in NEHGR 173:197-205, Isaac is the son of Bartholomew and Mary Allerton of East Bergholt (Suffolk) England. The article also says that Isaac was apprenticed to London blacksmith James Glyn but Isaac broke out of that contract and went to Holland.

Historical
1587: England - Queen Elizabeth authorizes the execution of Mary, Queen of Scots, for allegedly plotting against her
1588: England, Spain - England (with help from the weather) defeats the Spanish Armada
1589: Spain, England - Spain repulses the English Armada
1590: United States - Roanoke, Virginia "disappears", becoming "The Lost Colony"
1591: Morocco, Mali - In Mali, Moroccan forces of the Sultan Ahmad al-Mansur led by Judar Pasha defeat the Songhai Empire at the Battle of Tondibi
1591: Poland, Russia - Gazi Giray leads a huge Tatar/Tartar expedition against Moscow
1592-1593: England - John Stow reports 10,675 plague deaths in London, a city of approximately 200,000 people
1592-1598: Korea, China, Japan - Korea, with the help of Ming Dynasty China, repels two Japanese Invasions
1593-1606: Austria, Turkey - The Long War between the Habsburg monarchy and the Ottoman Turks
1598-1613: Russia - Russia descends into anarchy during the Time of Troubles
1598: France - The Edict of Nantes (one of the coolest names ever!) ends the French Wars of Religion
1600: Italy - Giordano Bruno is burned at the stake for heresy in Rome
1600: Japan - Battle of Sekigahara in Japan, end of the Warring States period and beginning of the Edo period
1601-1603: Russia - The Russian famine of 1601-1603 kills perhaps a third of Russia
1601: Ireland - Battle of Kinsale, one of the most Important battles in Irish history, fought
1601: Romania, Austria - Michael the Brave (first unificator of Romania), voivode of Wallachia, Moldavia and Transylvania, is assassinated by the order of the Habsburg general Giorgio Basta at Campia TurzII
1602: Netherlands - Dutch East India Company founded, Its success contributes to the Dutch Golden Age
1603-1623: Iran, Turkey, Portugal - After modernizing his army, Abbas I expands the Persian Empire by capturing territory from the Ottomans and the Portuguese
1603: England, Scotland - Elizabeth I of England dies and is succeeded by her cousin King James VI of Scotland, uniting the crowns of Scotland and England
1603: Japan - Tokugawa Ieyasu seizes control of Japan and establishes the Tokugawa Shogunate which rules the country until 1868
1605: England - Gunpowder Plot failed in England
1605: Turkey, Hungary - The fortresses of Veszprem en Visegrad in Hungary are retaken by the Ottomans
1606: Netherlands, Australia - Captain Willem Janszoon and his crew aboard the Dutch East India Company ship Duyfken becomes the first recorded Europeans to sight and make landfall in Australia
1606: Turkey, Austria - The Long War between the Ottoman Empire and Austria is ended with the Peace of Zsitvatorok
1607: Ireland - Flight of the Earls (the fleeing of most of the native Gaelic aristocracy) occurs from County Donegal in the west of Ulster in Ireland
1607: United States - Jamestown, Virginia, is settled as what would become the first permanent English colony in North America
1608: Canada - Quebec City founded by Samuel de Champlain in New France (present-day Canada)
1609: Germany - Maximilian of Bavaria establishes the Catholic League
1609: Netherlands, Spain - The Netherlands and Spain agree to a Twelve Years Truce in the Eighty Years War
1609: United States - Pedro de Peralta, a later governor of New Mexico, establishes the settlement of Santa Fe
1610: France - King Henry IV of France is assassinated and is succeeded by his nine year old son, King Louis XIII who rules until 1643
1610: Poland, Lithuania, Russia, Sweden - Battle of Klushino, the Polish Lithuanian Commonwealth army defeats combined Russian-Swedish forces and conquers Moscow
1612: England - King James version of the Bible is published
1613-1617: Poland, Lithuania - Polish-Lithuanian Commonwealth is Invaded by the Tatars (or Tartars) dozens of times
1613: Russia - The Time of Troubles in Russia ends with the establishment of the House of Romanov which rules until 1917
1613: United States - Pochahontas marries John Rolfe
1616: England - William Shakespeare dies
1616: Spain - The last remaining Moriscos (Moors who had nominally converted to Christianity) in the Spain are expelled
1618-1638: Germany - The Bohemian Revolt precipitates the Thirty Years War which devastates Europe in the years 1618-1648
1618: China - The Manchus start Invading China, their conquest eventually topples the Ming Dynasty
1618: Romania - Bethlen Gabor, Prince of Transylvania, joins Protestant Rebels
1619: Austria, Romania - Bethlen Gabor is defeated outside Vienna
1620-1621: Poland, Turkey - Polish-Ottoman War over Moldavia
1620: Poland - Battle of White Mountain, Emperor Ferdinand II, Holy Roman Emperor, defeats the Bohemian rebels
1620: Romania, Turkey - Bethlen Gabor allies with the Ottomans and an Invasion of Moldavia takes place, the Polish suffer a disaster at Cecora on the River Prut
1620: United States - The Puritan Pilgrims arrive in the Mayflower at Cape Cod
1621: Poland, Turkey - The Battle of Chocim Poles and Cossacks under Jan Karol Chodkiewicz defeat the Ottomans
1621: United States - The Pilgrims celebrate the first Thanksgiving with their Indian neighbors
1622: United States - Jamestown massacre Algonquian natives kill 347 English settlers outside Jamestown, Virginia (a third of the population of the colony) and burn the Henricus settlement
1623: Italy - Maffeo Barberini is elected Pope Urban VIII at the Papal conclave of 1623
1624-1642: France - As chief minister, Cardinal Richelieu centralises power in France
1625: United States - New Amsterdam founded by the Dutch West India Company in North America
1626: Italy - St. Peters Basilica in the Vatican completed
1626: United States - The Dutch buy Manhattan Island for $24, a presence is established but no large settlements made
1627: France - Cardinal Richelieu lays siege to Protestant La Rochelle which eventually capitulates
1629: France - Cardinal Richelieu allies with Swedish Protestant forces in the Thirty Years War to counter expansion by Ferdinand II
1631: Italy - Mount Vesuvius erupts near Naples
1632: germany - Battle of Lutzen (first of two), death of king of Sweden Gustav II Adolf
1633: Italy - Galileo Galilei arrives in Rome for his trial before the Inquisition
1633: United States - The city of Baltimore is settled
1634: Ethiopia - Emperor Fasilides expels the Catholic Patriarch Afonso Mendes and several Jesuit missionaries from Ethiopia
1634: Germany - Battle of Nordlingen (first of two), in Bavaria, results in Catholic victory
1636: Ethiopia - Emperor Fasilides founds the city of Gondar, which becomes the capital of Ethiopia for the next two centuries
1636: United States - Harvard University is founded in Cambridge, Massachusetts
1636: United States - Roger Williams is driven from Puritan Massachusetts and settles Rhode Island, a haven for religious freedom
1638: United States - Delaware is settled by Peter Minuet
1639-1651: England, Ireland, Scotland - Wars of the Three Kingdoms, civil wars throughout Scotland, Ireland, and England
1639: Italy - Disagreements between the Farnese and Barberini Pope Urban VIII escalate into the Wars of Castro and last until 1649
1639: Spain, England - Naval Battle of the Downs, Republic of the United Provinces fleet decisively defeats a Spanish fleet in English waters
1639: United States - John Wheelwright is banished from Boston and founds a colony in New Hampshire
1640-1668: Portugal - The Portuguese Restoration War led to the end of the Iberian Union
1640: England - Torture is outlawed in England
1640: Scotland - King Charles was compelled to summon Parliament due to the revolt of the Scots
1640: United States - The population of the American Colonies is estimated at 5,700. Starting in the 1990's, Charles Anderson of the New England Historic Genealogical Society begins books that provides information about all persons in New England by 1640.
1641: France - Rene Descartes publishes Meditationes de prima philosophia Meditations on First Philosophy
1641: Ireland - The Irish Rebellion
1641: Japan - The Tokugawa Shogunate Institutes Sakoku, foreigners are expelled and no one is allowed to enter or leave Japan
1642-1649: England - Civil War in England, Charles I is beheaded by Cromwell
1642: England - Isaac Newton is born
1642: Neatherlands, New Zealand - Dutch explorer Abel Janszoon Tasman achieves the first recorded European sighting of New Zealand
1644-1674: Mauritania - The Mauritanian Thirty-Year War
1644: China - The Manchu conquer China ending the Ming Dynasty, the subsequent Qing Dynasty rules until 1912
1644: Italy - Giovanni Battista Pamphili is elected Pope Innocent X at the Papal conclave of 1644
1645-1669: Turkey, Italy - Ottoman war with Venice, the Ottomans Invade Crete and capture Canea
1645: Japan - The death of Miyamoto Musashi, legendary Japanese Samurai warrior of natural causes
1647-1652: Spain - The Great Plague of Seville
1647: Turkey - Seven-year-old Mehmed IV becomes Ottoman sultan
1648-1653: France - Fronde civil war in France
1648-1667: Poland, Lithuania - The Deluge wars leave Polish-Lithuanian Commonwealth in ruins
1648-1669: Turkey, Italy - The Ottomans capture Crete from the Venetians after the Siege of Candia
1648: Spain, Italy - The Peace of Westphalia ends the Thirty Years War and the Eighty Years War and marks the ends of Spain and the Holy Roman Empire as major European powers
1649-1653: Ireland - The Cromwellian conquest of Ireland
1650: United States - An estimated 40,000 people are living in the American Colonies
1652: England, Netherlands - Anglo-Dutch Wars begin
1652: South Africa - Cape Town founded by the Dutch East India Company in South Africa
1654-1661: Turkey, Albania - Mehmed Koprulu is Grand Vizier
1655-1661: Sweden - The Northern Wars cement the rise of Sweden as a Great Power
1658: India - After his father Shah Jahan completes the Taj Mahal, his son Aurangzeb deposes him as ruler of the Mughal Empire