Sebastian was the son of Francisco A. Metzler born in Germany and Ana Diaz, the daughter of Jesus Diaz of Magdalena, Sonora, Mexico and Josefa Valenzuela of Guaymas, Sonora. Francisco, Sebastian's father, was a widower when he married Ana in 1881 in Hermosillo, Sonora. He was the father of eight children from his marriage to Eulogia Garcia Samaniego. The children were born between 1862 and 1877, and after Francisco's marriage to Ana, she helped raise the younger children .
Francisco and Ana had children of their own between 1885 and 1895 in Sonora, Mexico. Sebastian was their oldest followed by Rosaura, Antonio, Enrique, Ana Maria, and Maria Guadalupe.
Sebastian married Maria Campoy in Cananea, Sonora, Mexico, on November 27, 1912. Sebastian had resided in Cananea for five years, and Maria had been a resident there for eight years.
The young couple soon moved to Los Angeles, California where Sebastian's parents lived. They became parents of nine children, all born in Los Angeles with the exception of their daughter Bertha Consuelo Metzler who was born in Cananea. Their children include Alberto "Albert" Metzler born 9/1/1913, Emma Metzler born 4/8/1915, Armida Metzler born 7/27/1916, Bertha Consuelo Metzler born 2/21/1920, Sebastian J. "Johnny" Metzler born 3/11/1922, Kinardo "Kino" Metzler born 4/24/1924, Lou "Lewis" Metzler born 11/3/1927, Antonio Metzler born 5/8/1932 (stillborn) and Robert Metzler born 8/16/1936.
Son Albert enlisted in the U.S. Navy and served with the Sea Bee Battalion that took part on Day One of the Normandy Invasion during WWII. Sons Johnny, Kinardo and Robert also served in the U.S. Military. The spouse of their daughter Armida, Robert V. Bandurraga, served with the United States Army Air Corps.
Sebastian was a tailor by profession . Sometime after 1940, he moved to Naco, Arizona, where his brother Frank and family lived, and he resided there until his death at the Douglas Hospital in 1960.