Recorded in over forty spelling forms from Lambert, Lambard and Limprecht, to Lambrich, Lambertini and Lemmens, this surname is almost certainly of very early German origins. As a surname it started life in the 12th century, but the derivation is from a pre 5th century personal name.
Sheldon was raised in Galveston, Texas along with his elder brother and fraternal twin sister (Missy) by his mother, Mary Cooper, an overtly devout Evangelical Christian; and George Cooper, an alcoholic who was never around.
Priya Koothrappali is Raj's younger sister. She first appeared in The Irish Pub Formulation and serves as the unintentional main antagonist of season 4 in that Penny regards Priya as Leonard's most viable alternative girlfriend. Though she often looks annoyed or exasperated, she can be quite funny.