Efraim and Menashe Seidenbeutels were born on 6th June 1902 into a poor Jewish family in Warsaw. Their father was a book-keeper who ran a textile business in Warsaw, and the twins had six siblings. Their older brother Józef, who also pursued a painting career, introduced the twins to art, but died of TB in 1923 – the same year Menashe was admitted to the Fine Arts School in Warsaw.
Story has it that during the first year of their studies, the brothers took turns in attending classes, so that they would pay only one student fee. When the truth finally came out, the rector of the school decided that the twins would continue studying with only one fee. At school, their friends called them Sashe and Menashe.
The pair not only looked the same, but they also dressed the same. This however, as Tadeusz Wittlin recounted, was not caused by their willingness to confuse others, but rather because, 'they just had the same taste':
He always dresses the same: blue sport jacket, white shirt, crimson tie with a thick knot, grey flannel pants like pipes, brown Derby shoes that would never get a clean-up, and a light grey hat with a greasy black ribbon, tilted to the back.