Who was the sister of Marie Antoinette?

Answer 1

Well, she had a lot of sisters. Here's a list of all her siblings:

• Archduchess Maria Elisabeth of Austria February 5, 1737 June 6, 1740 died in childhood.
• Archduchess Maria Anna October 6, 1738 November 19, 1789 died unmarried, no issue.
• Archduchess Maria Karolina of Austria January 12, 1740 January 25, 1741 died in childhood.
• Joseph II March 13, 1741 February 20, 1790 married 1) Infanta Isabel of Spain (1741-1763), married 2) Princess Marie Josepha of Bavaria (1739-1767) - second cousin, had issue from his first marriage (two daughters, who died young)
• Archduchess Maria Christina of Austria May 13, 1742 June 24, 1798 married second-cousin Prince Albert of Saxony, Duke of Teschen (1739-1822) , had issue (one stillborn daughter)
• Archduchess Maria Elisabeth of Austria August 13, 1743 September 22, 1808 died unmarried, no issue
• Archduke Charles Joseph of Austria February 1, 1745 January 18, 1761 died of smallpox, no issue
• Archduchess Maria Amalia of Austria February 26, 1746 June 9, 1804 married Ferdinand, Duke of Parma (1751-1802), had issue.
• Holy Roman Emperor Leopold II May 5, 1747 March 1, 1792 married Infanta Maria Louisa of Spain (1745-1792), had issue. Grand Duke of Tuscany from 1765 (abdicated 1790), Holy Roman Emperor from 1790, Archduke of Austria, King of Hungary and King of Bohemia from 1790.
• Archduchess Maria Carolina September 17, 1748 September 17, 1748 stillborn
• Archduchess Maria Johanna Gabriela of Austria February 4, 1750 December 23, 1762 died of smallpox, no issue
• Archduchess Maria Josepha of Austria March 19, 1751 October 15, 1767 died of smallpox, no issue
• Archduchess Maria Carolina of Austria August 13, 1752 September 7, 1814 married King Ferdinand IV of Naples and Sicily (1751-1825); had issue
• Archduke Ferdinand of Austria, Duke of Breisgau June 1, 1754 December 24, 1806 married Maria Beatrice d'Este, heiress of Breisgau and of Modena, had issue (Austria-Este). Duke of Breisgau from 1803.
• Archduchess Maria Antonia of Austria November 2, 1755 October 16, 1793 married Louis XVI of France (1754-1793) and became the famous Queen Marie Antoinette, had issue
• Archduke Maximilian Franz of Austria December 8, 1756 July 27, 1801 Archbishop-Elector of Cologne, 1784. died unmarried, no issue

Answer 2

Marie Antoinette had four children and adopted three. Her children were Marie-Therese-Charlotte, Lois-Joseph, Louis-Charles and Sophie-Beatrix. Her adopted children were a maid's daughter (to King Louis), Marie-Philippine Lambriquet (Ernestine), later renamed by Marie Antoinette, Zoe, and Armand.