Andras Simonyi is the son of Denes Simonyi and Maria (Maca) Balazs. Denes Simonyi was the son of Leopold (Pal) Sommer (b. July 8, 1879) and Paula Beke Sommer (b. November 3, 1884). Denes was born on February 28, 1917 in Mosonmagyaróvár where his father was a merchant. Paula Sommer was the niece of the noted mathematician, Mano Beke. Denes had two older brothers. Bandi was born in 1910. He was married in Hungary and then moved to Belgium in 1934 where he co-owned a textile factory. Pista was born in 1913, and he survived the war in Budapest. After completing his education, Denes worked as a textile engineer in the factory of his maternal uncle, Lajos Beke in Csepel. While working in Csepel, Denes was conscripted for a forced labor battalion in 1941. The battalion, consisting of Jewish forced laborers, was sent to various locations to provide support services for a regular Hungarian army unit. They first were in Köszeg and then went to Zombar, Yugoslavia in May 1941. Denes spent July and August 1941 in Transylvania and the winter in Sighet. Denes returned home for a short furlough in 1942, and when he returned to his brigade, he was sent to Zalaegerszeg in 1943. He was then dispatched to the Soviet front the same year. However, after the defeat of the Hungarian 2nd Army by the Don in 1943, the Soviets arrested Denes and sent him to a POW camp in Gorky. Ironically, the Soviets arrested Jewish labor battalion conscripts along with the Hungarian soldiers. However, once they arrived in the camp, the Jewish prisoners, who listed their nationality as Jewish, were separated from the other Hungarians. Denes remained in the camp until September 1947, two years after the war ended.
After returning to Hungary, Denes met Maria (Maca) Balazs, a Catholic woman from Vac. During the last year of the war she helped deliver baptismal certificates to Jews about to be deported and succeeded in pulling them off the deportation trains from the station in Hatvan. The two married in 1949, and she later converted to Judaism and assumed the name Miriam. Denes' parents Leopold (Pal) Sommer and Paula Beke Sommerboth were deported from Papa to Auschwitz in early June 1944, where they perished. Denes's uncle, Lajos Beke, his wife and daughter Eva Beke [Mrs. Arpad Mallath] and her two-month old daughter born in April 1944 also perished in Auschwitz.